Cardiac conduction system evaluation

ABSTRACT

Systems, interfaces, and methods are described herein related to the evaluation of a patient&#39;s cardiac conduction system and evaluation of cardiac conduction system pacing therapy being delivered to the patient&#39;s cardiac conduction system. Evaluation of the patient&#39;s cardiac conduction system may utilize a plurality of breakthrough maps to determine where a cardiac conduction system block may be located. Evaluation of cardiac conduction system pacing therapy may utilize various electrical heterogeneity information monitored before and during delivery of cardiac conduction system pacing therapy.

This application claims the benefit of U.S. Provisional Patent Application Ser. No. 63/059,472 filed on Jul. 31, 2020, and entitled “Cardiac Conduction System Evaluation,” which is incorporated by reference herein in its entirety.

The disclosure herein relates to systems and methods for use in evaluating cardiac conduction system pacing therapy and cardiac conduction system block locations.

Implantable medical devices (IMDs), such as implantable pacemakers, cardioverters, defibrillators, or pacemaker-cardioverter-defibrillators, provide therapeutic electrical stimulation to the heart. IMDs may provide pacing to address bradycardia, or pacing or shocks in order to terminate tachyarrhythmia, such as tachycardia or fibrillation. In some cases, the medical device may sense intrinsic depolarizations of the heart, detect arrhythmia based on the intrinsic depolarizations (or absence thereof), and control delivery of electrical stimulation to the heart if arrhythmia is detected based on the intrinsic depolarizations.

IMDs may also provide cardiac resynchronization therapy (CRT), which is a form of pacing. CRT involves the delivery of pacing to the left ventricle, or both the left and right ventricles. The timing and location of the delivery of pacing pulses to the ventricle(s) may be selected to improve the coordination and efficiency of ventricular contraction.

Systems for implanting medical devices may include workstations or other equipment in addition to the implantable medical device itself. In some cases, these other pieces of equipment assist the physician or other technician with placing the intracardiac leads at particular locations on or in the heart. In some cases, the equipment provides information to the physician about the electrical activity of the heart and the location of the intracardiac lead.

SUMMARY

The illustrative systems and methods described herein may be configured to assist a user (e.g., a physician) in evaluating a patient's cardiac conduction system and in evaluating cardiac conduction system pacing therapy being delivered to a patient. In particular, the illustrative systems and methods may determine a cardiac conduction system block location based on breakthrough maps generated by monitoring cardiac electrical activity of a patient using a plurality of external electrodes disposed proximate the patient's skin. Further, the illustrative systems and methods may evaluate cardiac conduction system pacing therapy being delivered to a patient by comparing electrical heterogeneity information (EHI) acquired prior to delivery of cardiac conduction system pacing therapy to EHI acquired during delivery of cardiac conduction system pacing therapy.

In one or more embodiments, the systems and methods may be described as being noninvasive. For example, in some embodiments, the systems and methods may not need, or include, implantable devices such as leads, probes, sensors, catheters, implantable electrodes, etc. to monitor, or acquire, electrical activity (e.g., a plurality of cardiac signals) from tissue of the patient for use in evaluating the patient's cardiac conduction system and cardiac conduction system pacing therapy delivered to the patient's cardiac conduction system. Instead, the systems and methods may use electrical measurements taken noninvasively using, e.g., a plurality of external electrodes attached to the skin of a patient about the patient's torso. Additionally, it is be understood that both invasive and non-invasive apparatus and processes may be used at the same time or simultaneously in some embodiments.

It may be described that illustrative systems and methods (e.g., including electrode apparatus or ECG belt) may be used with cardiac conduction system pacing, various CRT procedures involving use of conduction system pacing with or without traditional coronary sinus left ventricular pacing. Additionally, the illustrative systems and methods can be used for intraprocedural planning and guidance on choice of conduction system pacing/device/leads to personalize therapy and provide the best resynchronization in every patient. Further, it may be described that the illustrative systems and methods provide multi-electrode ECGs that provides activation times, metrics of electrical dyssynchrony like standard deviation of activation times (SDAT), dispersion of left ventricular activation times, average left ventricular activation time, with or without combination of other metrics derived from ECG morphology.

The illustrative systems and methods may analyze, or evaluate, cardiac conduction system pacing leads implanted in locations close to the left bundle branch area, left ventricular septum, triangle of Koch in the right atrium, or His Bundle. Cardiac conduction system pacing may be delivered from those locations with varying pacing locations/parameters, and the illustrative systems and methods may determine a degree of efficacy of resynchronization and engagement of the cardiac conduction system or parts of the cardiac conduction system (e.g. left bundle, right bundle, etc.) based on change (e.g., from baseline to cardiac conduction system pacing) and absolute values (e.g., during cardiac conduction system pacing) of at least one of the metrics derived from electrical activity monitored by a plurality of external electrodes as described herein. If an adequate degree of resynchronization and/or engagement of the cardiac conduction system or parts of the cardiac conduction system is not achieved, then a traditional pacing lead (e.g., coronary sinus left ventricular lead) may be implanted and a degree of efficacy of resynchronization and engagement of the cardiac conduction system may be re-evaluated with pacing alone from that lead and in combination with the cardiac conduction system pacing lead. The decision of which lead to implant may be based on activation time maps during pacing alone from the cardiac conduction system pacing lead and/or the baseline/intrinsic activation maps. In particular, the location of the delay on the anterior map in both intrinsic and paced rhythm may be identified. If a dominant and persistent delay is identified in the right ventricular activation indicating a right bundle branch block, then a traditional right ventricular pacing lead may be implanted in the right ventricle. If a dominant and persistent delay is identified in the left ventricular activation indicating a left bundle branch block, then a traditional left ventricular pacing lead may be implanted in the coronary sinus. Further, a final implant decision may be taken based on resynchronization and efficacy of engagement of conduction system from both leads with different parameters, which also feeds into post-implant optimization.

One illustrative system may include an electrode apparatus comprising a plurality of external electrodes to be disposed proximate a patient's skin and computing apparatus comprising processing circuitry and coupled to the electrode apparatus. The computer apparatus may be configured to monitor intrinsic electrical activity of the patient using the plurality of external electrodes of the electrode apparatus, generate baseline electrical heterogeneity information (EHI) based on the monitored intrinsic electrical activity, monitor paced electrical activity of the patient using the plurality of external electrodes of the electrode apparatus during delivery of cardiac conduction system pacing therapy, generate paced EHI based on the monitored paced electrical activity, and determine whether the cardiac conduction system pacing therapy is effective based on the baseline and the paced EHI.

One illustrative method may include monitoring intrinsic electrical activity of the patient using a plurality of external electrodes disposed proximate the patient's skin, generating baseline electrical heterogeneity information (EHI) based on the monitored intrinsic electrical activity, monitoring paced electrical activity of the patient using the plurality of external electrodes of the electrode apparatus during delivery of cardiac conduction system pacing therapy, generating paced EHI based on the monitored paced electrical activity, and determining whether the cardiac conduction system pacing therapy is effective based on the baseline and the paced EHI.

The illustrative systems and methods may be described as surface mapping potential breakthroughs for determining locations of conduction block in cardiac conduction system disease. Proximal His-bundle pacing or more distal left bundle branch area pacing has been shown to be effective for resynchronization in patients with proximal conduction system disease (PCSD). However, not all left bundle block patients have a proximal block. Instead, there are patients where the block may be located more distally. The illustrative systems and methods may utilize ECG surface mapping that provides simultaneous measurements of depolarization complexes over multiple electrodes over the body-surface covering anterior as well as posterior locations. While the primary output is often activation times, alternative visualization of electrical activity may include spatial maps of potentials or voltages for each millisecond over multiple electrodes during the depolarization process. Location of left-sided breakthrough during intrinsic rhythm may help identify whether the block in a left bundle patient is proximal or more distal. Accordingly, a patient may receive therapy using leads targeting His or left bundle pacing (in the case of PCSD) or more distal pacing (e.g., mid-septal or apical septal or even traditional lateral wall pacing) in case the block is more distal. The illustrative systems and methods may utilize the location of left-sided potential breakthroughs from ECG belt maps to determine the location of conduction block in left bundle branch blocs, and accordingly, select therapy options for the patient.

In one or more embodiments, the illustrative systems and methods may provide spatial maps of potentials over anterior and posterior surfaces that are presented for every millisecond (ms) from QRS onset to QRS offset. The left side of the torso may be defined by regions to the left of the sternum and posteriorly to the left of the spine. The location of the first potential breakthrough on the left side may be recorded on the map. First potential breakthrough may be defined by a negative gradient of −0.5 millivolts (mV) over a given electrode over one ms during the depolarization process. The first potential breakthrough identifies the location where electrical activity first appears on the surface of the patient. If the location of the earliest left sided breakthrough is in the left anterior region of the torso, it will be determined that the patient has a more distal cardiac conduction system disease and may not be suitable for His bundle or left bundle area pacing for correction of left bundle. Conversely, if breakthrough occurs on the left posterior aspect of the torso, then the block in the cardiac conduction system may be more proximal and the patient may be amenable to correction of left bundle branch block by pacing from His bundle or left bundle branch area pacing. Thus, it may be described that noninvasive mapping of cardiac conduction system blocks to assist in planning therapy for correcting cardiac conduction system disorders.

One illustrative system may include an electrode apparatus comprising a plurality of external electrodes to be disposed proximate a patient's skin and a computing apparatus comprising processing circuitry and operably coupled to the electrode apparatus. The computing apparatus may be configured to monitor intrinsic electrical activity of the patient using the plurality of external electrodes of the electrode apparatus and generate a plurality of cardiac breakthrough maps based on the monitored intrinsic activity over a time period, where each cardiac breakthrough map is a spatial representation of electrocardiographic potential. The computing apparatus may be further configured to determine a cardiac conduction system block location based on the plurality of generated cardiac breakthrough maps.

One illustrative method may include monitoring intrinsic electrical activity of the patient using a plurality of external electrodes disposed proximate a patient's skin, generating a plurality of cardiac breakthrough maps based on the monitored intrinsic activity over a time period, where each cardiac breakthrough map is a spatial representation of electrocardiographic potential, and determining a cardiac conduction system block location based on the plurality of generated cardiac breakthrough maps.

One illustrative system may include an electrode apparatus comprising a plurality of external electrodes to be disposed proximate a patient's skin, a display comprising a graphical user interface, and a computing apparatus comprising processing circuitry and operably coupled to the electrode apparatus and the display. The computing apparatus may be configured to monitor intrinsic electrical activity of the patient using the plurality of external electrodes of the electrode apparatus, generate a plurality of cardiac breakthrough maps based on the monitored intrinsic activity over a time period, where each cardiac breakthrough map is a spatial representation of electrocardiographic potential, and display the plurality of generated cardiac breakthrough maps on the graphical user interface.

The above summary is not intended to describe each embodiment or every implementation of the present disclosure. A more complete understanding will become apparent and appreciated by referring to the following detailed description and claims taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram of an illustrative system including electrode apparatus, display apparatus, and computing apparatus.

FIGS. 2-3 are diagrams of illustrative external electrode apparatus for measuring torso-surface potentials.

FIG. 4A depicts a patient's cardiac conduction network including a cardiac conduction system block positioned between the atrioventricular node and the bundle of His.

FIG. 4B depicts a patient's cardiac conduction network including a cardiac conduction system block positioned in the left branch.

FIG. 5 is a block diagram of an illustrative method of evaluating a patient's cardiac conduction system.

FIGS. 6A-6B depict illustrative anterior and posterior cardiac breakthrough maps.

FIG. 6C depicts illustrative graphical user interface including the anterior and posterior cardiac breakthrough maps of FIG. 6B.

FIG. 7 is a block diagram of an illustrative method of evaluating cardiac conduction system pacing therapy.

FIG. 8 is a conceptual diagram of an illustrative cardiac therapy system including an intracardiac medical device implanted in a patient's heart and a separate medical device positioned outside of the patient's heart.

FIG. 9 is an enlarged conceptual diagram of the intracardiac medical device of FIG. 8 and anatomical structures of the patient's heart.

FIG. 10 is a conceptual diagram of a map of a patient's heart in a standard 17 segment view of the left ventricle showing various electrode implantation locations for use with the illustrative systems and devices described herein.

FIG. 11 is a block diagram of illustrative circuitry that may be enclosed within the housing of the medical devices of FIGS. 8-9 , for example, to provide the functionality and therapy described herein.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

In the following detailed description of illustrative embodiments, reference is made to the accompanying figures of the drawing which form a part hereof, and in which are shown, by way of illustration, specific embodiments which may be practiced. It is to be understood that other embodiments may be utilized, and structural changes may be made without departing from (e.g., still falling within) the scope of the disclosure presented hereby.

Illustrative systems and methods shall be described with reference to FIGS. 1-11 . It will be apparent to one skilled in the art that elements or processes from one embodiment may be used in combination with elements or processes of the other embodiments, and that the possible embodiments of such systems and methods using combinations of features set forth herein is not limited to the specific embodiments shown in the Figures and/or described herein. Further, it will be recognized that the embodiments described herein may include many elements that are not necessarily shown to scale. Still further, it will be recognized that timing of the processes and the size and shape of various elements herein may be modified but still fall within the scope of the present disclosure, although certain timings, one or more shapes and/or sizes, or types of elements, may be advantageous over others.

Various illustrative systems, methods, and graphical user interfaces may be configured to use electrode apparatus including external electrodes, display apparatus, and computing apparatus to noninvasively assist a user (e.g., a physician) in the evaluation of a patient's cardiac conduction system and the evaluation cardiac conduction system pacing therapy and/or the configuration (e.g., optimization) thereof, and potentially, in conjunction with traditional cardiac pacing therapy. An illustrative system 100 including electrode apparatus 110, computing apparatus 140, and a remote computing device 160 is depicted in FIG. 1 .

The electrode apparatus 110 as shown includes a plurality of electrodes incorporated, or included, within a band wrapped around the chest, or torso, of a patient 114. The electrode apparatus 110 is operatively coupled to the computing apparatus 140 (e.g., through one or wired electrical connections, wirelessly, etc.) to provide electrical signals from each of the electrodes to the computing apparatus 140 for analysis, evaluation, etc. Illustrative electrode apparatus may be described in U.S. Pat. No. 9,320,446 entitled “Bioelectric Sensor Device and Methods” filed Mar. 27, 2014 and issued on Mar. 26, 2016, which is incorporated herein by reference in its entirety. Further, illustrative electrode apparatus 110 will be described in more detail in reference to FIGS. 2-3 .

The computing apparatus 140 and the remote computing device 160 may each include display apparatus 130, 170, respectively, that may be configured to display data such as, e.g., electrical signals (e.g., electrocardiogram data), cardiac breakthrough maps, surface electrocardiographic potential maps, electrical activation times, electrical heterogeneity information, etc. For example, one cardiac cycle, or one heartbeat, of a plurality of cardiac cycles, or heartbeats, represented by the electrical signals collected or monitored by the electrode apparatus 110 may be analyzed and evaluated for one or more metrics including activation times and electrical heterogeneity information that may be pertinent to the assessment and evaluation of a patient's cardiac conduction system and/or cardiac conduction system pacing therapy delivered thereto. More specifically, for example, the QRS complex of a single cardiac cycle may be evaluated for one or more metrics such as, e.g., QRS onset, QRS offset, QRS peak, various electrical heterogeneity information (EHI) such as electrical activation times, left ventricular or thoracic standard deviation of electrical activation times (LVED), left ventricular dispersion, standard deviation of activation times (SDAT), average left ventricular or thoracic surrogate electrical activation times (LVAT), and referenced to earliest activation time, QRS duration (e.g., interval between QRS onset to QRS offset), difference between average left surrogate and average right surrogate activation times, relative or absolute QRS morphology, differences between a higher percentile and a lower percentile of activation times (higher percentile may be 90%, 80%, 75%, 70%, etc. and lower percentile may be 10%, 15%, 20%, 25% and 30%, etc.), other statistical measures of central tendency (e.g., median or mode), dispersion (e.g., mean deviation, standard deviation, variance, interquartile deviations, range), etc. Further, each of the one or more metrics may be location specific. For example, some metrics may be computed from signals recorded, or monitored, from electrodes positioned about a selected area of the patient such as, e.g., the left side of the patient, the right side of the patient, etc.

In at least one embodiment, one or both of the computing apparatus 140 and the remote computing device 160 may be a server, a personal computer, or a tablet computer. The computing apparatus 140 may be configured to receive input from input apparatus 142 (e.g., a keyboard) and transmit output to the display apparatus 130, and the remote computing device 160 may be configured to receive input from input apparatus 162 (e.g., a touchscreen) and transmit output to the display apparatus 170. One or both of the computing apparatus 140 and the remote computing device 160 may include data storage that may allow for access to processing programs or routines and/or one or more other types of data, e.g., for analyzing a plurality of electrical signals captured by the electrode apparatus 110, for determining cardiac breakthrough maps, a spatial representation of electrocardiographic potential, EHI, QRS onsets, QRS offsets, medians, modes, averages, peaks or maximum values, valleys or minimum values, electrical activation times, location of cardiac conduction system blocks along the cardiac conduction system (e.g., more proximal, more distal, etc.), whether the patient has left or right ventricular delays or blocks, whether one or more adjustments to pacing settings of cardiac therapy may provide effective therapy (e.g., provide improvement in cardiac resynchronization, provide improvement in cardiac heterogeneity), for driving a graphical user interface configured to noninvasively assist a user in configuring cardiac conduction system pacing therapy with or without traditional pacing therapy, one or more pacing parameters, or settings, related to such cardiac conduction system pacing therapy and/or traditional pacing therapy such as, e.g., pacing rate, ventricular pacing rate, A-V interval, V-V interval, pacing pulse width, pacing vector, multipoint pacing vector (e.g., left ventricular vector quad lead), pacing voltage, pacing configuration (e.g., biventricular pacing, right ventricle only pacing, left ventricle only pacing, etc.), and for arrhythmia detection and treatment, etc.

The computing apparatus 140 may be operatively coupled to the input apparatus 142 and the display apparatus 130 to, e.g., transmit data to and from each of the input apparatus 142 and the display apparatus 130, and the remote computing device 160 may be operatively coupled to the input apparatus 162 and the display apparatus 170 to, e.g., transmit data to and from each of the input apparatus 162 and the display apparatus 170. For example, the computing apparatus 140 and the remote computing device 160 may be electrically coupled to the input apparatus 142, 162 and the display apparatus 130, 170 using, e.g., analog electrical connections, digital electrical connections, wireless connections, bus-based connections, network-based connections, internet-based connections, etc. As described further herein, a user may provide input to the input apparatus 142, 162 to view and/or select one or more of a plurality of cardiac breakthrough maps over time and electrical heterogeneity information.

Although as depicted the input apparatus 142 is a keyboard and the input apparatus 162 is a touchscreen, it is to be understood that the input apparatus 142, 162 may include any apparatus capable of providing input to the computing apparatus 140 and the computing device 160 to perform the functionality, methods, and/or logic described herein. For example, the input apparatus 142, 162 may include a keyboard, a mouse, a trackball, a touchscreen (e.g., capacitive touchscreen, a resistive touchscreen, a multi-touch touchscreen, etc.), etc. Likewise, the display apparatus 130, 170 may include any apparatus capable of displaying information to a user, such as a graphical user interface 132, 172 including electrode status information, graphical maps of cardiac breakthrough, graphical maps of electrocardiographic potential, graphical maps of electrical activation, indications of location of cardiac conduction system block (e.g., proximally along the cardiac conduction system, distally along the cardiac conduction system, etc.), a plurality of signals for the external electrodes over one or more heartbeats, QRS complexes, various cardiac therapy scenario selection regions, various rankings of cardiac therapy scenarios, various pacing parameters, electrical heterogeneity information (EHI), textual instructions, graphical depictions of anatomy of a human heart, images or graphical depictions of the patient's heart, graphical depictions of locations of one or more electrodes, graphical depictions of a human torso, images or graphical depictions of the patient's torso, graphical depictions or actual images of implanted electrodes and/or leads, etc. Further, the display apparatus 130, 170 may include a liquid crystal display, an organic light-emitting diode screen, a touchscreen, a cathode ray tube display, etc.

It is to be understood that the computing apparatus 140 and the remote computing device 160 may be operatively coupled to each other in a plurality of different ways so as to perform, or execute, the functionality described herein. For example, in the embodiment depicted, the computing device 140 may be wireless operably coupled to the remote computing device 160 as depicted by the wireless signal lines emanating therebetween. Additionally, as opposed to wireless connections, one or more of the computing apparatus 140 and the remoting computing device 160 may be operably coupled through one or wired electrical connections.

The processing programs or routines stored and/or executed by the computing apparatus 140 and the remote computing device 160 may include programs or routines for computational mathematics, matrix mathematics, decomposition algorithms, compression algorithms (e.g., data compression algorithms), calibration algorithms, image construction algorithms, signal processing algorithms (e.g., various filtering algorithms, Fourier transforms, fast Fourier transforms, etc.), standardization algorithms, comparison algorithms, vector mathematics, or any other processing used to implement one or more illustrative methods and/or processes described herein. Data stored and/or used by the computing apparatus 140 and the remote computing device 160 may include, for example, electrical signal/waveform data from the electrode apparatus 110 (e.g., electrocardiographic potential or voltage over time, a plurality of QRS complexes, etc.), electrical activation times from the electrode apparatus 110, cardiac sound/signal/waveform data from acoustic sensors, graphics (e.g., graphical elements, icons, buttons, windows, dialogs, pull-down menus, graphic areas, graphic regions, 3D graphics, etc.), graphical user interfaces, results from one or more processing programs or routines employed according to the disclosure herein (e.g., electrical signals, electrical heterogeneity information, etc.), or any other data that may be used for executing, or performing, the one and/or more processes or methods described herein.

In one or more embodiments, the illustrative systems, methods, and interfaces may be implemented using one or more computer programs executed on programmable computers, such as computers that include, for example, processing capabilities, data storage (e.g., volatile or non-volatile memory and/or storage elements), input devices, and output devices. Program code and/or logic described herein may be applied to input data to perform the functionality described herein and generate desired output information. The output information may be applied as input to one or more other devices and/or methods as described herein or as would be applied in a known fashion.

The one or more programs used to implement the systems, methods, and/or interfaces described herein may be provided using any programmable language, e.g., a high-level procedural and/or object orientated programming language that is suitable for communicating with a computer system. Any such programs may, for example, be stored on any suitable device, e.g., a storage media, that is readable by a general or special purpose program running on a computer system (e.g., including processing apparatus) for configuring and operating the computer system when the suitable device is read for performing the procedures described herein. In other words, at least in one embodiment, the illustrative systems, methods, and interfaces may be implemented using a computer readable storage medium, configured with a computer program, where the storage medium so configured causes the computer to operate in a specific and predefined manner to perform functions described herein. Further, in at least one embodiment, the illustrative systems, methods, and interfaces may be described as being implemented by logic (e.g., object code) encoded in one or more non-transitory media that includes code for execution and, when executed by a processor or processing circuitry, is operable to perform operations such as the methods, processes, and/or functionality described herein.

The computing apparatus 140 and the remote computing device 160 may be, for example, any fixed or mobile computer system (e.g., a controller, a microcontroller, a personal computer, minicomputer, tablet computer, etc.). The exact configurations of the computing apparatus 140 and the remote computing device 160 are not limiting, and essentially any device capable of providing suitable computing capabilities and control capabilities (e.g., signal analysis, mathematical functions such as medians, modes, averages, maximum value determination, minimum value determination, slope determination, minimum slope determination, maximum slope determination, graphics processing, etc.) may be used. As described herein, a digital file may be any medium (e.g., volatile or non-volatile memory, a CD-ROM, a punch card, magnetic recordable tape, etc.) containing digital bits (e.g., encoded in binary, trinary, etc.) that may be readable and/or writeable by the computing apparatus 140 and the remote computing device 160 described herein. Also, as described herein, a file in user-readable format may be any representation of data (e.g., ASCII text, binary numbers, hexadecimal numbers, decimal numbers, graphically, etc.) presentable on any medium (e.g., paper, a display, etc.) readable and/or understandable by a user.

In view of the above, it will be readily apparent that the functionality as described in one or more embodiments according to the present disclosure may be implemented in any manner as would be known to one skilled in the art. As such, the computer language, the computer system, or any other software/hardware which is to be used to implement the processes described herein shall not be limiting on the scope of the systems, processes, or programs (e.g., the functionality provided by such systems, processes, or programs) described herein.

The illustrative electrode apparatus 110 may be configured to measure body-surface potentials of a patient 114 and, more particularly, torso-surface potentials of a patient 114. As shown in FIG. 2 , the illustrative electrode apparatus 110 may include a set, or array, of external electrodes 112, a strap 113, and interface/amplifier circuitry 116. The electrodes 112 may be attached, or coupled, to the strap 113 and the strap 113 may be configured to be wrapped around the torso of a patient 114 such that the electrodes 112 surround the patient's heart. As further illustrated, the electrodes 112 may be positioned around the circumference of a patient 114, including the posterior, lateral, posterolateral, anterolateral, and anterior locations of the torso of a patient 114.

The illustrative electrode apparatus 110 may be further configured to measure, or monitor, sounds from the patient 114 (e.g., heart sounds from the torso of the patient). As shown in FIG. 2 , the illustrative electrode apparatus 110 may include a set, or array, of acoustic sensors 120 attached, or coupled, to the strap 113. The strap 113 may be configured to be wrapped around the torso of a patient 114 such that the acoustic sensors 120 surround the patient's heart. As further illustrated, the acoustic sensors 120 may be positioned around the circumference of a patient 114, including the posterior, lateral, posterolateral, anterolateral, and anterior locations of the torso of a patient 114.

Further, the electrodes 112 and the acoustic sensors 120 may be electrically connected to interface/amplifier circuitry 116 via wired connection 118. The interface/amplifier circuitry 116 may be configured to amplify the signals from the electrodes 112 and the acoustic sensors 120 and provide the signals to one or both of the computing apparatus 140 and the remote computing device 160. Other illustrative systems may use a wireless connection to transmit the signals sensed by electrodes 112 and the acoustic sensors 120 to the interface/amplifier circuitry 116 and, in turn, to one or both of the computing apparatus 140 and the remote computing device 160, e.g., as channels of data. In one or more embodiments, the interface/amplifier circuitry 116 may be electrically coupled to one or both of the computing apparatus 140 and the remote computing device 160 using, e.g., analog electrical connections, digital electrical connections, wireless connections, bus-based connections, network-based connections, internet-based connections, etc.

Although in the example of FIG. 2 the electrode apparatus 110 includes a strap 113, in other examples any of a variety of mechanisms, e.g., tape or adhesives, may be employed to aid in the spacing and placement of electrodes 112 and the acoustic sensors 120. In some examples, the strap 113 may include an elastic band, strip of tape, or cloth. Further, in some examples, the strap 113 may be part of, or integrated with, a piece of clothing such as, e.g., a t-shirt. In other examples, the electrodes 112 and the acoustic sensors 120 may be placed individually on the torso of a patient 114. Further, in other examples, one or both of the electrodes 112 (e.g., arranged in an array) and the acoustic sensors 120 (e.g., also arranged in an array) may be part of, or located within, patches, vests, and/or other manners of securing the electrodes 112 and the acoustic sensors 120 to the torso of the patient 114. Still further, in other examples, one or both of the electrodes 112 and the acoustic sensors 120 may be part of, or located within, two sections of material or two patches. One of the two patches may be located on the anterior side of the torso of the patient 114 (to, e.g., monitor electrical signals representative of the anterior side of the patient's heart, measure surrogate cardiac electrical activation times representative of the anterior side of the patient's heart, monitor or measure sounds of the anterior side of the patient, etc.) and the other patch may be located on the posterior side of the torso of the patient 114 (to, e.g., monitor electrical signals representative of the posterior side of the patient's heart, measure surrogate cardiac electrical activation times representative of the posterior side of the patient's heart, monitor or measure sounds of the posterior side of the patient, etc.). And still further, in other examples, one or both of the electrodes 112 and the acoustic sensors 120 may be arranged in a top row and bottom row that extend from the anterior side of the patient 114 across the left side of the patient 114 to the posterior side of the patient 114. Yet still further, in other examples, one or both of the electrodes 112 and the acoustic sensors 120 may be arranged in a curve around the armpit area and may have an electrode/sensor-density that is less dense on the right thorax that the other remaining areas.

The electrodes 112 may be configured to surround the heart of the patient 114 and record, or monitor, the electrical signals associated with the depolarization and repolarization of the heart after the signals have propagated through the torso of a patient 114. Each of the electrodes 112 may be used in a unipolar configuration to sense the torso-surface potentials that reflect the cardiac signals. The interface/amplifier circuitry 116 may also be coupled to a return or indifferent electrode (not shown) that may be used in combination with each electrode 112 for unipolar sensing.

In some examples, there may be about 12 to about 50 electrodes 112 and about 12 to about 50 acoustic sensors 120 spatially distributed around the torso of a patient. Other configurations may have more or fewer electrodes 112 and more or fewer acoustic sensors 120. It is to be understood that the electrodes 112 and acoustic sensors 120 may not be arranged or distributed in an array extending all the way around or completely around the patient 114. Instead, the electrodes 112 and acoustic sensors 120 may be arranged in an array that extends only part of the way or partially around the patient 114. For example, the electrodes 112 and acoustic sensors 120 may be distributed on the anterior, posterior, and left sides of the patient with less or no electrodes and acoustic sensors proximate the right side (including posterior and anterior regions of the right side of the patient).

One or both of the computing apparatus 140 and the remote computing device 160 may record and analyze the torso-surface potential signals sensed by electrodes 112 and the sound signals sensed by the acoustic sensors 120, which are amplified/conditioned by the interface/amplifier circuitry 116. Further, one or both of the computing apparatus 140 and the remote computing device 160 may be configured to analyze the electrical signals from the electrodes 112 to provide electrocardiogram (ECG) signals, information such as EHI, or data from the patient's heart as will be further described herein. Still further, one or both of the computing apparatus 140 and the remote computing device 160 may be configured to analyze the electrical signals from the acoustic sensors 120 to provide sound signals, information, or data from the patient's body and/or devices implanted therein (such as a left ventricular assist device).

Additionally, the computing apparatus 140 and the remote computing device 160 may be configured to provide graphical user interfaces 132, 172 depicting various information related to the electrode apparatus 110 and the data gathered, or sensed, using the electrode apparatus 110. For example, the graphical user interfaces 132, 172 may depict cardiac breakthrough maps, electrocardiographic potential maps, electrical activation maps, and EHI obtained using the electrode apparatus 110. For example, the graphical user interfaces 132, 172 may depict ECGs including QRS complexes obtained using the electrode apparatus 110 and sound data including sound waves obtained using the acoustic sensors 120 as well as other information related thereto. Illustrative systems and methods may noninvasively use the electrical information collected using the electrode apparatus 110 and the sound information collected using the acoustic sensors 120 to evaluate a patient's cardiac health and to evaluate and configure cardiac therapy being delivered to the patient. More specifically, the illustrative systems and methods may noninvasively use the electrical information collected using the electrode apparatus 110 to determine a cardiac conduction system block location and/or to evaluate cardiac conduction system pacing therapy with or without being used in conjunction with traditional pacing therapy.

Further, the electrode apparatus 110 may further include reference electrodes and/or drive electrodes to be, e.g. positioned about the lower torso of the patient 114, that may be further used by the system 100. For example, the electrode apparatus 110 may include three reference electrodes, and the signals from the three reference electrodes may be combined to provide a reference signal. Further, the electrode apparatus 110 may use three caudal reference electrodes (e.g., instead of standard reference electrodes used in a Wilson Central Terminal) to get a “true” unipolar signal with less noise from averaging three caudally located reference signals.

FIG. 3 illustrates another illustrative electrode apparatus 110 that includes a plurality of electrodes 112 configured to surround the heart of the patient 114 and record, or monitor, the electrical signals associated with the depolarization and repolarization of the heart after the signals have propagated through the torso of the patient 114 and a plurality of acoustic sensors 120 configured to surround the heart of the patient 114 and record, or monitor, the sound signals associated with the heart after the signals have propagated through the torso of the patient 114. The electrode apparatus 110 may include a vest 114 upon which the plurality of electrodes 112 and the plurality of acoustic sensors 120 may be attached, or to which the electrodes 112 and the acoustic sensors 120 may be coupled. In at least one embodiment, the plurality, or array, of electrodes 112 may be used to collect electrical information such as, e.g., surrogate electrical activation times. Similar to the electrode apparatus 110 of FIG. 2 , the electrode apparatus 110 of FIG. 3 may include interface/amplifier circuitry 116 electrically coupled to each of the electrodes 112 and the acoustic sensors 120 through a wired connection 118 and be configured to transmit signals from the electrodes 112 and the acoustic sensors 120 to computing apparatus 140. As illustrated, the electrodes 112 and the acoustic sensors 120 may be distributed over the torso of a patient 114, including, for example, the posterior, lateral, posterolateral, anterolateral, and anterior locations of the torso of a patient 114.

The vest 114 may be formed of fabric with the electrodes 112 and the acoustic sensors 120 attached to the fabric. The vest 114 may be configured to maintain the position and spacing of electrodes 112 and the acoustic sensors 120 on the torso of the patient 114. Further, the vest 114 may be marked to assist in determining the location of the electrodes 112 and the acoustic sensors 120 on the surface of the torso of the patient 114. In some examples, there may be about 25 to about 256 electrodes 112 and about 25 to about 256 acoustic sensors 120 distributed around the torso of the patient 114, though other configurations may have more or fewer electrodes 112 and more or fewer acoustic sensors 120.

A patient's cardiac conduction network 200 is depicted in FIGS. 4A-4B. As shown, the cardiac conduction network 200 extends from a proximal region 222 to a distal region 224. The cardiac conduction network 200 includes a specialized network of cells comprising the left and right bundle branches as well as a highly-branched network of specialized Purkinje fibers that aids in rapid propagation of electrical activation across the ventricles, which may lead to a very synchronized activation of the heart. The cardiac conduction system is part of the natural pathway of electrical conduction that extends from the sinoatrial node 230 to the ventricles via the atrioventricular node 232. Further, the electrical impulses that trigger depolarization of the myocardial tissue of the patient's heart to effectively “beat” traverse the cardiac conduction network 200 from the sinoatrial node 230 to the Purkinje fibers 239.

As described, herein, the proximal region 222 of the cardiac conduction network 200 may include the sinoatrial node 230 and the atrioventricular node 232 and the intermodal pathways therebetween, and the distal region 224 of the cardiac conduction network 200 may include the right bundle branch 238, the left posterior bundle 236, and the Purkinje fibers 239. In particular, the most distal area of the cardiac conduction network 200 may be the ends of the Purkinje fibers 239 and the most proximal area of the cardiac conduction network 200 may be the sinoatrial node 230. Thus, the cardiac conduction network 200 may be described as extending from the sinoatrial node 230 to the Purkinje fibers 239.

In FIG. 4A, a cardiac conduction system block 240 is positioned just distal of the atrioventricular node 232 but prior to the bundle of His 234 branching to the left and right bundles. Thus, it may be described that the cardiac conduction system block 240 is positioned relatively proximally along the cardiac conduction network 220. Using the illustrative systems and methods as will be described further herein, a plurality of breakthrough maps may be used determine where the cardiac conduction system block 240 is positioned as shown in FIG. 4A. Since the cardiac conduction system block 240 is located relatively proximally (e.g., closer to the proximal region 222 than the distal region 224), it may be a good candidate for cardiac conduction system pacing therapy because, e.g., cardiac conduction system pacing therapy may be delivered to a position, or location, within the cardiac conduction system distal of the cardiac conduction system block 240. For example, cardiac conduction system pacing therapy may be delivered to the bundle of His 234 and/or one of both of the right and left branches.

In FIG. 4B, a cardiac conduction system block 241 is positioned along the left branch just distal of the left posterior bundle. Thus, it may be described that the cardiac conduction system block 241 is positioned relatively distally along the cardiac conduction network 220. Using the illustrative systems and methods as will be described further herein, a plurality of breakthrough maps may be used determine where the cardiac conduction system block 241 is positioned as shown in FIG. 4B. Since the cardiac conduction system block 241 is located relatively distally (e.g., closer to the distal region 224 than the proximal region 222), the cardiac conduction system block 241 may not be a good candidate for cardiac conduction system pacing therapy because, e.g., cardiac conduction system pacing therapy likely could not be positioned more distal than the cardiac conduction system block 241, and if the cardiac conduction system pacing therapy were positioned proximal to the cardiac conduction system block 241 (such as, e.g., at the bundle of his 234), any such cardiac conduction system pacing therapy may be blocked, or stopped, by the cardiac conduction system block 241. Therefore, when comparing the cardiac conduction system blocks 240, 241 of FIGS. 4A-4B, the more proximal cardiac conduction system block 240 is likely more correctable using cardiac conduction system pacing therapy than the more distal cardiac conduction system block 241 of FIG. 4B.

The illustrative systems, methods, and interfaces described herein may be used to provide noninvasive assistance to a user in the evaluation and assessment patients cardiac conduction system, and in particular, the location of a cardiac conduction system block along the cardiac conduction system. For instance, the illustrative systems, methods, and interfaces may utilize a plurality of cardiac breakthrough maps to determine an approximate location along the cardiac conduction system where a cardiac conduction system block is located.

Further, the illustrative systems and methods described herein may provide users a useful tool to determine where a cardiac conduction system block is located or relatively positioned within the cardiac conduction network of a patient. For example, the illustrative systems and methods may determine how proximal or distal a cardiac conduction system block is located along the cardiac conduction network of the patient. The location of the cardiac conduction system block may be helpful in determining whether cardiac conduction system pacing therapy and/or another cardiac therapy may be successful in treating the patient.

An illustrative method 300 of evaluating a patient's cardiac conduction system is depicted in FIG. 5 . Generally, it may be described that the illustrative method 300 may be used to analyze external electrical activity (e.g., from the skin of the torso of the patient) prior to delivery of any cardiac pacing therapy and use such electrical activity to determine where along the cardiac conduction system are block is located, which may guide a clinician in determining where to deliver therapy.

The method 300 may include monitoring electrical activity 302. In one embodiment, the electrical activity may be measured externally from the patient. In other words, the electrical activity may be measured from tissue outside the patient's body (e.g., skin). For example, the method 300 may include monitoring, or measuring, electrical activity 302 using a plurality of external electrodes such as, e.g., shown and described with respect to FIGS. 1-3 . In one embodiment, the plurality of external electrodes may be part, or incorporated into, a vest or band that is located about a patient's torso. More specifically, the plurality of electrodes may be described as being external surface electrodes positioned in an array configured to be located proximate the skin of the torso of a patient. It may be described that when using a plurality of external electrodes, the monitoring process 302 may provide a plurality electrocardiograms (ECGs), electrocardiographic potential or voltage, signals representative of the depolarization and repolarization of the patient's heart, and/or a plurality of activation times.

In particular in method 300, the monitored electrical activity 302 may be used to generate a plurality of cardiac breakthrough maps 304. Each of the plurality of cardiac breakthrough maps is a spatial representation of electrocardiographic potential of the patient's heart. The plurality of cardiac breakthrough maps when viewed or depicted in sequence show the spatial representation of electrocardiographic potential of the patient's heart over time. In this way, the plurality of cardiac breakthrough maps may be described as a video of the spatial representation of electrocardiographic potential of the patient's heart (e.g., during a cardiac cycle), that can be traversed forward and backward.

Illustrative anterior and posterior cardiac breakthrough maps are depicted in FIGS. 6A-6B. Each cardiac breakthrough map includes an anterior region corresponding to the electrical activity (e.g., electrocardiographic potential) measured from the anterior of the patient's torso and a posterior region corresponding to the electrical activity (e.g., electrocardiographic potential) measured from the posterior of the patient's torso. As shown, the anterior region extends from a right side of the patient to a left side of the patient and the posterior region extends from the left side of the patient to the right side of the patient so as to depict the breakthrough map wrapping around the torso of the patient.

As described, the cardiac breakthrough maps depict the electrocardiographic potential across the skin of the patient (which corresponds to the heart of the patient) for a given or selected time. For example, the cardiac breakthrough maps of each of FIGS. 6A-6B are depicted at 25 milliseconds (ms) after QRS onset. The illustrative method 230, however, generates a plurality of cardiac breakthrough maps 304 according to a sample interval. The sampling interval may be between about 0.5 ms and 10 ms. In at least one embodiment, the sampling interval is 5 ms. In other embodiments, the sampling interval may greater than or equal to 0.5 ms, greater than or equal to 0.75 ms, greater than or equal to 1 ms, greater than or equal to 2.5 ms, etc. and/or less than or equal to about 10 ms, less than or equal to about 7 ms, less than or equal to about 5 ms, less than or equal to about 3 ms, less than or equal to about 2 ms, etc. Thus, for example, if the sampling interval is 5 ms and breakthrough maps are generated for 500 ms following QRS onset, 100 breakthrough maps may be generated.

Although QRS onset is described herein as the triggering, or initiating, event for generating cardiac breakthrough maps, it is be understood that any triggering, or initiating, event may be used to begin generating cardiac breakthrough maps. In at least one embodiment, the triggering, or initiating, event may be selected such that ventricular depolarization is captured so that cardiac breakthrough may be identified within the cardiac breakthrough maps.

Additionally, the plurality of cardiac breakthrough maps may be generated and analyzed for a single heartbeat at time. For example, the illustrative systems and methods described herein may determine the cardiac conduction system block location during a single heartbeat. It is to be understood, however, that the cardiac conduction system block location may be determined for multiple heartbeats, but only a single heartbeat may be analyzed at a time.

The illustrative method 300 may further include determining a cardiac conduction system block location based on the plurality of generated cardiac breakthrough maps 306. In other words, the plurality of generated cardiac breakthrough maps may be used to determine a cardiac conduction system block location. Generally, it may be described that, if the spatial location of the cardiac breakthrough is located in a left anterior region according to the plurality of cardiac breakthrough maps, then it may be determined that the cardiac conduction system block is located distally along the cardiac conduction system, and conversely, if the spatial location of the cardiac breakthrough is not located in a left anterior region according to the plurality of cardiac breakthrough maps, then it may be determined that the cardiac conduction system block is located proximally along the cardiac conduction system.

More specifically, determining a cardiac conduction system block location based on the plurality of generated cardiac breakthrough maps 306 may include first determining the spatial location of the cardiac breakthrough within the plurality of cardiac breakthrough maps 308. Determination of the spatial location of the cardiac breakthrough within the plurality of cardiac breakthrough maps 308 may be performed or executed in a variety of different manners. Generally, determination of the spatial location of the cardiac breakthrough within the plurality of cardiac breakthrough maps 308 is looking for the first surface location where ventricular depolarization substantively occurs and accordingly infer the location of the first myocardial breakthrough proximate to the first surface location (e.g., underneath the first surface location on the heart).

In one example, a breakthrough threshold may be utilized to determine the spatial location of the cardiac breakthrough. An illustrative breakthrough threshold may be between about −0.2 millivolts (mV) and about −1.5 mV. In at least one embodiment, the breakthrough threshold may be −1 mV. When utilizing the breakthrough threshold, the first location or region that generates a cardiac potential that less than or equal to the breakthrough threshold may be identified as the spatial location of the cardiac breakthrough.

For example, each of the cardiac breakthrough maps depicted in FIGS. 6A-6B utilize the breakthrough threshold of −1 mV and are gray scaled (or color coded) accordingly with any electrocardiographic potential less than or equal to −1 mV depicted in a first gray scale (or color code) and any electrocardiographic potential greater than −1 mV depicted in a second gray scale (or color code) different than the first gray scale (or color code). In this way, when traversing a plurality of cardiac breakthrough maps, it may be apparent which cardiac breakthrough map first depicts the cardiac breakthrough. In both examples depicted in FIGS. 6A-6B, the cardiac breakthrough occurs at 25 ms after QRS onset.

Determining a cardiac conduction system block location based on the plurality of generated cardiac breakthrough maps 306 may further include determining whether the cardiac breakthrough is located in a left anterior region of the cardiac breakthrough maps 310. The left anterior region of the cardiac breakthrough maps may be captured from a left anterior subset of external positioned generally on the anterior of the patient's torso between the sternum and left side. An illustrative left anterior region is depicted by a dashed line box 316 in FIGS. 6A-6B.

If the cardiac breakthrough is located in the left anterior region such as shown in FIG. 6A, it may be determined that the cardiac conduction system block is distally located along the cardiac conduction system 312. Conversely, if the cardiac breakthrough is not located in the left anterior region such as shown in FIG. 6B, it may be determined that the cardiac conduction system block is proximally located along the cardiac conduction system 314.

As described herein, the cardiac conduction network 200 extends from a proximal region 222 to a distal region 224 as shown in FIGS. 4A-4B. When the method 300 determines that the cardiac conduction system block is proximally located along the cardiac conduction system 314, the cardiac conduction system block may be located closer to the proximal region 222 than the distal region 224. Conversely, when the method 300 determines that the cardiac conduction system block is distally located along the cardiac conduction system 314, the cardiac conduction system block may be located closer to the distal region 224 than the proximal region 222.

The plurality of cardiac breakthrough maps may be further used with an illustrative graphical user interface 311 as shown in FIG. 6C. As shown, the graphical user interface 311 includes a map region 313 for displaying cardiac breakthrough maps including anterior and posterior regions and a timeline region 315. The timeline region 315 may be used by a user to move through, or traverse through, the plurality of breakthrough maps time depicted in the map region 313. The timeline region 315 includes a marker 317 indicating the position along the timeline of the plurality of breakthrough maps generated over time based on the monitored electrical activity over time. A user may select the marker 317 and “drag” the marker 317 left to move to previous breakthrough maps corresponding to earlier time periods or “drag” the marker 317 right to move to later breakthrough maps corresponding to later time periods. As shown, the marker 317 is located at 25 ms after QRS onset. The breakthrough maps of FIG. 6B are depicted in the map region 313 of the graphical user interface 311 of FIG. 6C, which, as described herein, do not include a cardiac breakthrough located in the left anterior region thereby indicating the cardiac conduction system is located proximally along the cardiac conduction system. Thus, the graphical user interface 311 further includes a cardiac conduction system block indication 301 of whether the cardiac conduction system block location is proximally located or distally located along the cardiac conduction system. In this example, the cardiac conduction system block indication 301 indicates that the cardiac conduction system block location is proximally located.

The illustrative systems, methods, and interfaces described herein may be used to provide noninvasive assistance to a user in the evaluation and assessment of cardiac conduction system pacing therapy (e.g., by an implantable medical device such as a VfA pacing device) with or without being used in conjunction with traditional pacing therapy (e.g., left ventricular pacing lead in the coronary sinus to pace the left ventricle, a right ventricular pacing lead located in the right ventricle to pace the base of the right ventricle, etc.). Further, the illustrative systems, methods, and interfaces described herein may be able to assist a user in the improvement and configuration of cardiac conduction system pacing therapy.

An illustrative method 400 of evaluating cardiac conduction system pacing therapy is depicted in FIG. 7 . The method 400 may include monitoring electrical activity 402 to generate a plurality of electrical signals (e.g., ECG or cardiac signals). The electrical activity may be monitored during intrinsic heart rhythm of the patient without delivery of any cardiac therapy. Thus, the electrical activity may be monitored 402 prior to the implantation of any implantable cardiac therapy device. For example, the monitoring 402 may be performed during an initial consultation prior to any invasive procedures to treat the present condition. Additionally, as described herein, monitoring electrical activity 402 using a plurality of external electrodes is a noninvasive process since, e.g., the external electrodes are attached to the skin of the patient as opposed to inserting or implanting any electrodes to acquire electrical activity or data. Additionally, however, if an implantable cardiac therapy device is already implanted in the patient, the monitoring 402 may be performed with any cardiac therapy provided by the implantable cardiac therapy device disabled (or “turned off”).

According to various embodiments, the electrical activity is monitored 402 using a plurality of electrodes. The plurality of electrodes may be external surface electrodes configured in a band or a vest similar to as described herein with respect to FIGS. 1-3 . Each of the electrodes may be positioned or located about the torso of the patient so as to monitor electrical activity (e.g., acquire torso-potentials) from a plurality of different locations about the torso of the patient. Each of the different locations where the electrodes are located may correspond to the electrical activation of different portions or regions of cardiac tissue of the patient's heart. Thus, for example, the plurality of electrodes may record, or monitor, the electrical signals associated with the depolarization and repolarization of a plurality of different locations of, or about, the heart after the signals have propagated through the torso of a patient. According to various embodiments, the plurality of external electrodes may include, or comprise, a plurality of anterior electrodes that are located proximate skin of the anterior of the patient's torso, left lateral or left side electrodes that are located proximate skin of the left lateral or left side of the patient's torso, and posterior electrodes that are located proximate skin of the posterior of the patient's torso.

It may be described that, when using a plurality of external electrodes, the monitoring process 402 may provide a plurality electrocardiograms (ECGs), signals representative of the depolarization and repolarization of the patient's heart. The plurality of ECGs may, in turn, be used to generate surrogate cardiac electrical activation times representative of the depolarization of the heart. As described herein, surrogate cardiac electrical activation times may be, for example, representative of actual, or local, electrical activation times of one or more regions of the patient's heart. Measurement of activation times can be performed by picking an appropriate fiducial point (e.g., peak values, minimum values, minimum slopes, maximum slopes, zero crossings, threshold crossings, etc. of a near or far-field EGM) and measuring time between the onset of cardiac depolarization (e.g., onset of QRS complexes) and the appropriate fiducial point (e.g., within the electrical activity). The activation time between the onset of the QRS complex (or the peak Q wave) to the fiducial point may be referred to as q-LV time. In at least one embodiment, the earliest QRS onset from all of the plurality of electrodes may be utilized as the starting point for each activation time for each electrode, and the maximum slope following the onset of the QRS complex may be utilized as the end point of each activation time for each electrode.

The monitored electrical activity 402 and, in turn, the electrical activation times may be used to generate baseline (or intrinsic) electrical heterogeneity information (EHI) 404. The EHI (e.g., data) may be defined as information indicative of at least one of mechanical synchrony or dyssynchrony of the heart and/or electrical synchrony or dyssynchrony of the heart. In other words, EHI may represent a surrogate of actual mechanical and/or electrical functionality of a patient's heart. As will be further described herein, relative changes in EHI (e.g., from baseline heterogeneity information to paced, or therapy, heterogeneity information, from a first set of heterogeneity information to a second set of therapy heterogeneity information, etc.) may be used to determine a surrogate value representative of the changes in hemodynamic response (e.g., acute changes in LV pressure gradients). Left ventricular pressure may be typically monitored invasively with a pressure sensor located in the left ventricular of a patient's heart. As such, the use of EHI to determine a surrogate value representative of the left ventricular pressure may avoid invasive monitoring using a left ventricular pressure sensor.

In at least one embodiment, the EHI may include a standard deviation of ventricular activation times measured using some or all of the external electrodes, e.g., of the electrode apparatus 110 described herein with respect FIGS. 1-3 . Further, local, or regional, EHI may include standard deviations and/or averages of activation times measured using electrodes located in certain anatomic areas of the torso. For example, external electrodes on the left side of the torso of a patient may be used to compute local, or regional, left EHI.

The EHI may be generated using one or more various systems and/or methods. For example, EHI may be generated using an array, or a plurality, of surface electrodes and/or imaging systems as described in U.S. Pat. No. 9,510,763 B2 issued on Dec. 6, 2016, and entitled “ASSESSING INTRACARDIAC ACTIVATION PATTERNS AND ELECTRICAL DYSSYNCHRONY,” U.S. Pat. No. 8,972,228 B2 issued Mar. 3, 2015, and entitled “ASSESSING INTRACARDIAC ACTIVATION PATTERNS”, and U.S. Pat. No. 8,180,428 B2 issued May 15, 2012 and entitled “METHODS AND SYSTEMS FOR USE IN SELECTING CARDIAC PACING SITES,” each of which is incorporated herein by reference in its entirety.

EHI may include one or more metrics or indices. For example, one of the metrics, or indices, of electrical heterogeneity may be a standard deviation of activation times (SDAT) measured using some or all of the electrodes on the surface of the torso of a patient. In some examples, the SDAT may be calculated using the surrogate, or estimated, cardiac activation times over the surface of a model heart.

In this example, the EHI comprises one or more left, or left-sided, metrics generated based on left-sided activation times of the surrogate cardiac electrical activation times measured using a plurality of left external electrodes. The left external electrodes may include a plurality of left external electrodes positioned to the left side of the patient's torso.

One left, or left-sided metric, or index, of electrical heterogeneity, or dyssynchrony, may be a left-sided metric of dispersion such as, for example, a left standard deviation of surrogate cardiac electrical activation times (LVED) monitored by external electrodes located proximate the left side of a patient. Further, another left, or left-sided metric, or index, of electrical heterogeneity may include an average of surrogate cardiac electrical activation times (LVAT) monitored by external electrodes located proximate the left side of a patient. The LVED and LVAT may be determined (e.g., calculated, computed, etc.) from electrical activity measured only by electrodes proximate the left side of the patient, which may be referred to as “left” electrodes. Activation time determined, or measured, from the left electrodes may be described as being left-sided activation times. The left electrodes may be defined as any surface electrodes located proximate the left ventricle, which includes the body or torso regions to the left of the patient's sternum and spine (e.g., toward the left arm of the patient, the left side of the patient, etc.). In one embodiment, the left electrodes may include all anterior electrodes on the left of the sternum and all posterior electrodes to the left of the spine. In another embodiment, the left electrodes may include all anterior electrodes on the left of the sternum and all posterior electrodes. In yet another embodiment, the left electrodes may be designated based on the contour of the left and right sides of the heart as determined using imaging apparatus (e.g., x-ray, fluoroscopy, etc.).

The illustrative method 400 may then deliver cardiac conduction pacing therapy 406 using a cardiac conduction system pacing device. The cardiac conduction system pacing therapy may include pacing therapy that is configured to pace the cardiac conduction system of the patient. For example, the cardiac conduction system pacing therapy may include ventricle-from-atrium (VfA) pacing, which is further described herein with respect to FIGS. 8-11 . Further, for example, the cardiac conduction system pacing therapy may include His bundle pacing therapy such as described in, for example, U.S. Pat. App. Pub. No. 2019/0111270 A1 entitled “His Bundle and Bundle Branch Pacing Adjustment” published on Apr. 18, 2019, which is incorporated herein by reference in its entirety. Still further, for example, the cardiac conduction system pacing therapy may include intraseptal left ventricular endocardial pacing such as described in, for example, U.S. patent application Ser. No. 16/521,000 entitled “AV Synchronous Septal Pacing” filed on Jul. 24, 2019, which is incorporated herein by reference in its entirety.

The cardiac conduction system pacing therapy may be delivered according to various basic or nominal parameters. For example, the cardiac conduction system pacing therapy may be delivered at a paced AV delay that between 40% to 80% of an intrinsic AV delay. The paced AV delay is a time period between a sensed atrial event and delivery of cardiac conduction system pacing therapy, and the intrinsic AV delay is a time period between a sensed atrial event and an intrinsic ventricular event. The intrinsic AV delay may be monitored or measured prior the delivery of cardiac conduction system pacing therapy or during a pause in the delivery of cardiac conduction system pacing therapy.

During the delivery of cardiac conduction system pacing therapy 406, the method 400 may further include monitoring paced electrical activity of the patient using a plurality of external electrodes 407 and generating paced EHI 408 based on the monitored paced electrical activity. The electrical activity may be monitored 407 in the same or similar fashion as described herein with respect to process 402 except that it is monitored during the delivery of cardiac conduction system pacing therapy. Likewise, the paced EHI 408 may be generated 408 in the same or similar fashion as described herein with respect to process 404 except that the electrical activity used to generate the paced EHI was monitored during the delivery of cardiac conduction system pacing therapy.

As a result, the method 400 may now be described as having baseline EHI and paced EHI, which may be used to determine whether the cardiac conduction system pacing therapy is effective 410. One or more metrics of EHI may be used to determine whether the cardiac conduction system pacing therapy is effective.

For example, SDAT may be utilized to determine whether the cardiac conduction system pacing therapy is effective 410. More specifically, generating baseline EHI may include generating a baseline SDAT based on the monitored intrinsic electrical activity, and generating paced EHI may include generating a paced SDAT based on the monitored paced electrical activity. The baseline SDAT and the paced SDAT may then be utilized (e.g., compared) to determine whether the cardiac conduction system pacing therapy is effective 412. For instance, a reduction in SDAT from baseline to paced may be analyzed. In at least one embodiment, if the paced SDAT is less than 90% of the baseline SDAT, then it may be determined that the cardiac conduction system pacing therapy is effective 412. Conversely, if the paced SDAT is greater than or equal to 90% of the baseline SDAT, then it may be determined that the cardiac conduction system pacing therapy is not effective. In other words, a threshold SDAT percentage of paced SDAT to baseline SDAT may be used to determine whether the cardiac conduction system pacing therapy is effective or not effective. The threshold SDAT percentage may between about 70% and about 95%. As described earlier, the threshold SDAT percentage may be 90%. In other embodiments, the threshold SDAT percentage may be greater than or equal to 70%, greater than or equal to 80%, greater than or equal to 85%, etc. and/or less than or equal to 95%, less than or equal to 90%, etc.

Further, for example, an EHI metric of ventricular dispersion may be utilized to determine whether the cardiac conduction system pacing therapy is effective 410. More specifically, generating paced EHI may include generating a paced LVED based on the monitored paced electrical activity. The paced LVED may then be utilized (e.g., compared) to determine whether the cardiac conduction system pacing therapy is effective 412. For instance, the LVED may compared to a LVED threshold value. In at least one embodiment, if the paced LVED is greater than 25 milliseconds, then it may be determined that the cardiac conduction system pacing therapy is effective 412. Conversely, if the paced LVED is less than or equal to 25 ms, then it may be determined that the cardiac conduction system pacing therapy is not effective. In other words, a threshold LVED value may be used to determine whether the cardiac conduction system pacing therapy is effective or not effective. The threshold LVED value may between about 15 ms and about 40 ms. As described earlier, the threshold LVED value may be 25 ms. In other embodiments, the threshold LVED value may be greater than or equal to 15 ms, greater than or equal to 20 ms, greater than or equal to 30%, etc. and/or less than or equal to 40%, less than or equal to 35%, etc.

As described herein, one or more metrics of EHI may be used to determine whether the cardiac conduction system pacing therapy is effective 410. In at least one embodiment, change in SDAT from baseline to pacing (or therapy) and paced LVED may both be utilized to determine whether the cardiac conduction system pacing therapy is effective 412. For example, if the paced SDAT is less than 90% of the baseline SDAT and if the paced LVED is greater than 25 milliseconds less than the intrinsic LVED, then it may be determined that the cardiac conduction system pacing therapy is effective 412. Conversely, if the paced SDAT is greater than or equal to 90% of the baseline SDAT or if the paced LVED is less than or equal to 25 ms, then it may be determined that the cardiac conduction system pacing therapy is not effective. In other words, such test may be dependent on both metrics indicating effective cardiac conduction system pacing therapy to move forward and ultimately determine that the cardiac conduction system pacing therapy is effective; if one or none of the metrics do not indicate that the cardiac conduction system pacing therapy is effective, then it may be ultimately determined that the ccs pacing therapy is ineffective.

It is to be understood that when cardiac conduction system pacing therapy is described as being effective that the cardiac conduction system pacing therapy is acceptable to provide cardiac therapy without utilizing additional therapy such as traditional myocardial tissue cardiac pacing therapy (e.g., using a left ventricular lead in the coronary sinus to paced the myocardial tissue of the left ventricle, using a right ventricular lead in the right ventricle to pace the myocardial tissue of the right ventricle). Thus, if cardiac conduction system pacing therapy is not determined to be effective, it may mean that the cardiac conduction system pacing therapy is partially effective or not effective at all. In either case, additional cardiac therapy may need to be delivered to provide acceptable cardiac therapy to the patient.

Thus, the method 400 may further analyze the location of cardiac activation delay 414 if it is determined the cardiac conduction system pacing therapy is not effective. In particular, whether the cardiac activation delay is located on the right side or left side of the patient's heart, and in particular, the left ventricle, based on the monitored electrical activity may be determined 414. In other words, whether cardiac activation delay is located on the left or right side of the left ventricle based on the monitored paced electrical activity may be determined in response to determining that the cardiac conduction system pacing therapy is not effective.

For example, surrogate cardiac activation time maps may be generated for the anterior and posterior of the patient based on the monitoring intrinsic electrical activation and/or the monitored paced electrical activity, and the activation times, or delays, therein may be compared to an activation threshold. If the activation times are later than the activation threshold, then the area of the surrogate cardiac activation time maps corresponding to such late activation times may be determined to have cardiac activation delay. The activation threshold may be between about 25 ms and about 75 ms. In at least one embodiment, the activation threshold is 50 ms. In other embodiments, the activation threshold may be greater than or equal to 25 ms, greater than or equal to 35 ms, greater than or equal to 45 ms, greater than or equal to 55 ms, etc. and/or less than or equal to 75 ms, less than or equal to 65 ms, less than or equal to 60 ms, less than or equal to 50 ms, etc. For instance, if delayed activation occurs more on the anterior map in both intrinsic and paced rhythm, a dominant and persistent delay in right ventricular activation may be identified (e.g., a right bundle branch block patient) in which case the traditional pacing lead implanted may be a right ventricular pacing lead.

Thus, if the cardiac activation delay is located predominately on the left side, a left ventricular lead to pace the myocardial tissue of the left ventricle may be implanted 216. And, if the cardiac activation delay is located predominately on the right side, a right ventricular lead to pace the myocardial tissue of the right ventricle may be implanted 218.

The method 400 may then continue monitoring paced electrical activity 408 during delivery of cardiac conduction system pacing therapy and traditional pacing therapy using a right or left ventricular lead. In other words, cardiac conduction system pacing therapy may be delivered in conjunction with traditional pacing therapy, and electrical activity may be monitored during the delivery of such combined therapy. The monitored electrical activity may then be used to configure the right or left pacing lead 420. For example, combined paced EHI may be generated based on the monitored combined paced electrical activity. The combined EHI may then be used to determine the effectiveness of the combined pacing therapy. For example, the SDAT and/or LVED generated from electrical activity monitored during combined pacing therapy may be compared to baseline SDAT and/or baseline LVED and/or compared to various threshold values similar to as described herein with respect to process 410.

Additionally, during configuration of the pacing lead 420, one or more paced parameters may be adjusted such as, for example, pacing lead location, pacing amplitude or voltage, number of pulses, pacing burst length, pacing frequency, single or multiple electrode pacing vectors, etc. Each different parameter may be adjusted while monitoring the electrical activity of the combined pacing therapy and evaluating the EHI generated therefrom to determine the optimal set of pacing parameters. Further illustrative systems, methods, and processes for optimizing the cardiac pacing therapy may be described in U.S. patent application Ser. No. 15/934,517 filed on Mar. 23, 2019 entitled “Evaluation of Ventricle from Atrium Pacing Therapy” and U.S. Prov. Pat. App. Ser. No. 62/725,763 filed on Aug. 31, 2018 entitled “Adaptive VFA Cardiac Therapy,” each of which is incorporated herein by reference in its entirety.

An illustrative ventricle from atrium (VfA) cardiac therapy system is depicted in FIG. 8 that may be configured to be used with, for example, the systems and methods described herein with respect to FIGS. 1-7 . Although it is to be understood that the present disclosure may utilize one or both of leadless and leaded implantable medical devices, the illustrative cardiac therapy system of FIG. 8 includes a leadless intracardiac medical device 10 that may be configured for single or dual chamber therapy and implanted in a patient's heart 8. In some embodiments, the device 10 may be configured for single chamber pacing and may, for example, switch between single chamber and multiple chamber pacing (e.g., dual or triple chamber pacing). As used herein, “intracardiac” refers to a device configured to be implanted entirely within a patient's heart, for example, to provide cardiac therapy. The device 10 is shown implanted in the right atrium (RA) of the patient's heart 8 in a target implant region 4. The device 10 may include one or more fixation members 20 that anchor a distal end of the device 10 against the atrial endocardium in a target implant region 4. The target implant region 4 may lie between the Bundle of His 5 and the coronary sinus 3 and may be adjacent, or next to, the tricuspid valve 6. The device 10 may be described as a ventricle-from-atrium device because, for example, the device 10 may perform, or execute, one or both of sensing electrical activity from and providing therapy to one or both ventricles (e.g., right ventricle, left ventricle, or both ventricles, depending on the circumstances) while being generally disposed in the right atrium. In particular, the device 10 may include a tissue-piercing electrode that may be implanted in the basal and/or septal region of the left ventricular myocardium of the patient's heart from the triangle of Koch region of the right atrium through the right atrial endocardium and central fibrous body.

The device 10 may be described as a leadless implantable medical device. As used herein, “leadless” refers to a device being free of a lead extending out of the patient's heart 8. Further, although a leadless device may have a lead, the lead would not extend from outside of the patient's heart to inside of the patient's heart or would not extend from inside of the patient's heart to outside of the patient's heart. Some leadless devices may be introduced through a vein, but once implanted, the device is free of, or may not include, any transvenous lead and may be configured to provide cardiac therapy without using any transvenous lead. Further, a leadless VfA device, in particular, does not use a lead to operably connect to an electrode in the ventricle when a housing of the device is positioned in the atrium. Additionally, a leadless electrode may be coupled to the housing of the medical device without using a lead between the electrode and the housing.

The device 10 may include a dart electrode assembly 12 defining, or having, a straight shaft extending from a distal end region of device 10. The dart electrode assembly 12 may be placed, or at least configured to be placed, through the atrial myocardium and the central fibrous body and into the ventricular myocardium 14, or along the ventricular septum, without perforating entirely through the ventricular endocardial or epicardial surfaces. The dart electrode assembly 12 may carry, or include, an electrode at a distal end region of the shaft such that the electrode may be positioned within the ventricular myocardium for sensing ventricular signals and delivering ventricular pacing pulses (e.g., to depolarize the left ventricle and/or right ventricle to initiate a contraction of the left ventricle and/or right ventricle). In some examples, the electrode at the distal end region of the shaft is a cathode electrode provided for use in a bipolar electrode pair for pacing and sensing. While the implant region 4 as illustrated may enable one or more electrodes of the dart electrode assembly 12 to be positioned in the ventricular myocardium, it is recognized that a device having the aspects disclosed herein may be implanted at other locations for multiple chamber pacing (e.g., dual or triple chamber pacing), single chamber pacing with multiple chamber sensing, single chamber pacing and/or sensing, or other clinical therapy and applications as appropriate.

It is to be understood that although device 10 is described herein as including a single dart electrode assembly, the device 10 may include more than one dart electrode assembly placed, or configured to be placed, through the atrial myocardium and the central fibrous body, and into the ventricular myocardium 14, or along the ventricular septum, without perforating entirely through the ventricular endocardial or epicardial surfaces. Additionally, each dart electrode assembly may carry, or include, more than a single electrode at the distal end region, or along other regions (e.g., proximal or central regions), of the shaft.

The cardiac therapy system 2 may also include a separate medical device 50 (depicted diagrammatically in FIG. 8 ), which may be positioned outside the patient's heart 8 (e.g., subcutaneously) and may be operably coupled to the patient's heart 8 to deliver cardiac therapy thereto. In one example, separate medical device 50 may be an extravascular ICD. In some embodiments, an extravascular ICD may include a defibrillation lead including, or carrying, a defibrillation electrode. A therapy vector may exist between the defibrillation electrode on the defibrillation lead and a housing electrode of the ICD. Further, one or more electrodes of the ICD may also be used for sensing electrical signals related to the patient's heart 8. The ICD may be configured to deliver shock therapy including one or more defibrillation or cardioversion shocks. For example, if an arrhythmia is sensed, the ICD may send a pulse via the electrical lead wires to shock the heart and restore its normal rhythm. In some examples, the ICD may deliver shock therapy without placing electrical lead wires within the heart or attaching electrical wires directly to the heart (subcutaneous ICDs). Examples of extravascular, subcutaneous ICDs that may be used with the system 2 described herein may be described in U.S. Pat. No. 9,278,229 (Reinke et al.), issued 8 Mar. 2016, which is incorporated herein by reference in its entirety.

In the case of shock therapy (e.g., defibrillation shocks provided by the defibrillation electrode of the defibrillation lead), the separate medical device 50 (e.g., extravascular ICD) may include a control circuit that uses a therapy delivery circuit to generate defibrillation shocks having any of a number of waveform properties, including leading-edge voltage, tilt, delivered energy, pulse phases, and the like. The therapy delivery circuit may, for instance, generate monophasic, biphasic, or multiphasic waveforms. Additionally, the therapy delivery circuit may generate defibrillation waveforms having different amounts of energy. For example, the therapy delivery circuit may generate defibrillation waveforms that deliver a total of between approximately 60-80 Joules (J) of energy for subcutaneous defibrillation.

The separate medical device 50 may further include a sensing circuit. The sensing circuit may be configured to obtain electrical signals sensed via one or more combinations of electrodes and to process the obtained signals. The components of the sensing circuit may include analog components, digital components, or a combination thereof. The sensing circuit may, for example, include one or more sense amplifiers, filters, rectifiers, threshold detectors, analog-to-digital converters (ADCs), or the like. The sensing circuit may convert the sensed signals to digital form and provide the digital signals to the control circuit for processing and/or analysis. For example, the sensing circuit may amplify signals from sensing electrodes and convert the amplified signals to multi-bit digital signals by an ADC, and then provide the digital signals to the control circuit. In one or more embodiments, the sensing circuit may also compare processed signals to a threshold to detect the existence of atrial or ventricular depolarizations (e.g., P- or R-waves) and indicate the existence of the atrial depolarization (e.g., P-waves) or ventricular depolarizations (e.g., R-waves) to the control circuit.

The device 10 and the separate medical device 50 may cooperate to provide cardiac therapy to the patient's heart 8. For example, the device 10 and the separate medical device 50 may be used to detect tachycardia, monitor tachycardia, and/or provide tachycardia-related therapy. For example, the device 10 may communicate with the separate medical device 50 wirelessly to trigger shock therapy using the separate medical device 50. As used herein, “wirelessly” refers to an operative coupling or connection without using a metal conductor between the device 10 and the separate medical device 50. In one example, wireless communication may use a distinctive, signaling, or triggering electrical pulse provided by the device 10 that conducts through the patient's tissue and is detectable by the separate medical device 50. In another example, wireless communication may use a communication interface (e.g., an antenna) of the device 10 to provide electromagnetic radiation that propagates through patient's tissue and is detectable, for example, using a communication interface (e.g., an antenna) of the separate medical device 50.

FIG. 9 is an enlarged conceptual diagram of the intracardiac medical device 10 of FIG. 8 and anatomical structures of the patient's heart 8. In particular, the device 10 is configured to sense cardiac signals and/or deliver pacing therapy. The intracardiac device 10 may include a housing 30. The housing 30 may define a hermetically-sealed internal cavity in which internal components of the device 10 reside, such as a sensing circuit, therapy delivery circuit, control circuit, memory, telemetry circuit, other optional sensors, and a power source as generally described in conjunction with FIG. 11 . The housing 30 may include (e.g., be formed of or from) an electrically conductive material such as, e.g., titanium or titanium alloy, stainless steel, MP35N (a non-magnetic nickel-cobalt-chromium-molybdenum alloy), platinum alloy, or other bio-compatible metal or metal alloy. In other examples, the housing 30 may include (e.g., be formed of or from) a non-conductive material including ceramic, glass, sapphire, silicone, polyurethane, epoxy, acetyl co-polymer plastics, polyether ether ketone (PEEK), a liquid crystal polymer, or other biocompatible polymer.

In at least one embodiment, the housing 30 may be described as extending between a distal end region 32 and a proximal end region 34 and as defining a generally-cylindrical shape, e.g., to facilitate catheter delivery. In other embodiments, the housing 30 may be prismatic or any other shape to perform the functionality and utility described herein. The housing 30 may include a delivery tool interface member 26, e.g., defined, or positioned, at the proximal end region 34, for engaging with a delivery tool during implantation of the device 10.

All or a portion of the housing 30 may function as a sensing and/or pacing electrode during cardiac therapy. In the example shown, the housing 30 includes a proximal housing-based electrode 24 that circumscribes a proximal portion (e.g., closer to the proximal end region 34 than the distal end region 32) of the housing 30. When the housing 30 is (e.g., defines, formed from, etc.) an electrically-conductive material, such as a titanium alloy or other examples listed above, portions of the housing 30 may be electrically insulated by a non-conductive material, such as a coating of parylene, polyurethane, silicone, epoxy, or other biocompatible polymer, leaving one or more discrete areas of conductive material exposed to form, or define, the proximal housing-based electrode 24. When the housing 30 is (e.g., defines, formed from, etc.) a non-conductive material, such as a ceramic, glass or polymer material, an electrically-conductive coating or layer, such as a titanium, platinum, stainless steel, or alloys thereof, may be applied to one or more discrete areas of the housing 30 to form, or define, the proximal housing-based electrode 24. In other examples, the proximal housing-based electrode 24 may be a component, such as a ring electrode, that is mounted or assembled onto the housing 30. The proximal housing-based electrode 24 may be electrically coupled to internal circuitry of the device 10, e.g., via the electrically-conductive housing 30 or an electrical conductor when the housing 30 is a non-conductive material.

In the example shown, the proximal housing-based electrode 24 is located nearer to the housing proximal end region 34 than the housing distal end region 32, and therefore, may be referred to as a proximal housing-based electrode 24. In other examples, however, the proximal housing-based electrode 24 may be located at other positions along the housing 30, e.g., more distal relative to the position shown.

At the distal end region 32, the device 10 may include a distal fixation and electrode assembly 36, which may include one or more fixation members 20 and one or more dart electrode assemblies 12 of equal or unequal length. In one such example as shown, a single dart electrode assembly 12 includes a shaft 40 extending distally away from the housing distal end region 32 and one or more electrode elements, such as a tip electrode 42 at or near the free, distal end region of the shaft 40. The tip electrode 42 may have a conical or hemi-spherical distal tip with a relatively narrow tip-diameter (e.g., less than about 1 millimeter (mm)) for penetrating into and through tissue layers without using a sharpened tip or needle-like tip having sharpened or beveled edges.

The dart electrode assembly 12 may be configured to pierce through one or more tissue layers to position the tip electrode 42 within a desired tissue layer such as, e.g., the ventricular myocardium. As such, the height 47, or length, of the shaft 40 may correspond to the expected pacing site depth, and the shaft 40 may have a relatively-high compressive strength along its longitudinal axis to resist bending in a lateral or radial direction when pressed against and into the implant region 4. If a second dart electrode assembly 12 is employed, its length may be unequal to the expected pacing site depth and may be configured to act as an indifferent electrode for delivering of pacing energy to and/or sensing signals from the tissue. In one embodiment, a longitudinal axial force may be applied against the tip electrode 42, e.g., by applying longitudinal pushing force to the proximal end 34 of the housing 30, to advance the dart electrode assembly 12 into the tissue within the target implant region.

The shaft 40 may be described as longitudinally non-compressive and/or elastically deformable in lateral or radial directions when subjected to lateral or radial forces to allow temporary flexing, e.g., with tissue motion, but may return to its normally straight position when lateral forces diminish. Thus, the dart electrode assembly 12 including the shaft 40 may be described as being resilient. When the shaft 40 is not exposed to any external force, or to only a force along its longitudinal central axis, the shaft 40 may retain a straight, linear position as shown.

In other words, the shaft 40 of the dart electrode assembly 12 may be a normally straight member and may be rigid. In other embodiments, the shaft 40 may be described as being relatively stiff but still possessing limited flexibility in lateral directions. Further, the shaft 40 may be non-rigid to allow some lateral flexing with heart motion. However, in a relaxed state, when not subjected to any external forces, the shaft 40 may maintain a straight position as shown to hold the tip electrode 42 spaced apart from the housing distal end region 32 at least by a height, or length, 47 of the shaft 40.

The one or more fixation members 20 may be described as one or more “tines” having a normally curved position. The tines may be held in a distally extended position within a delivery tool. The distal tips of tines may penetrate the heart tissue to a limited depth before elastically, or resiliently, curving back proximally into the normally curved position (shown) upon release from the delivery tool. Further, the fixation members 20 may include one or more aspects described in, for example, U.S. Pat. No. 9,675,579 (Grubac et al.), issued 13 Jun. 2017, and U.S. Pat. No. 9,119,959 (Rys et al.), issued 1 Sep. 2015, each of which is incorporated herein by reference in its entirety.

In some examples, the distal fixation and electrode assembly 36 includes a distal housing-based electrode 22. In the case of using the device 10 as a pacemaker for multiple chamber pacing (e.g., dual or triple chamber pacing) and sensing, the tip electrode 42 may be used as a cathode electrode paired with the proximal housing-based electrode 24 serving as a return anode electrode. Alternatively, the distal housing-based electrode 22 may serve as a return anode electrode paired with tip electrode 42 for sensing ventricular signals and delivering ventricular pacing pulses. In other examples, the distal housing-based electrode 22 may be a cathode electrode for sensing atrial signals and delivering pacing pulses to the atrial myocardium in the target implant region 4. When the distal housing-based electrode 22 serves as an atrial cathode electrode, the proximal housing-based electrode 24 may serve as the return anode paired with the tip electrode 42 for ventricular pacing and sensing and as the return anode paired with the distal housing-based electrode 22 for atrial pacing and sensing.

As shown in this illustration, the target implant region 4 in some pacing applications is along the atrial endocardium 18, generally inferior to the AV node 15 and the His bundle 5. The dart electrode assembly 12 may at least partially define the height 47, or length, of the shaft 40 for penetrating through the atrial endocardium 18 in the target implant region 4, through the central fibrous body 16, and into the ventricular myocardium 14 without perforating through the ventricular endocardial surface 17. When the height 47, or length, of the dart electrode assembly 12 is fully advanced into the target implant region 4, the tip electrode 42 may rest within the ventricular myocardium 14, and the distal housing-based electrode 22 may be positioned in intimate contact with or close proximity to the atrial endocardium 18. The dart electrode assembly 12 may have a total combined height 47, or length, of tip electrode 42 and shaft 40 from about 3 mm to about 8 mm in various examples. The diameter of the shaft 40 may be less than about 2 mm, and may be about 1 mm or less, or even about 0.6 mm or less.

FIG. 10 is a two-dimensional (2D) ventricular map 319 of a patient's heart (e.g., a top-down view) showing the left ventricle 320 in a standard 17 segment view and the right ventricle 322. The map 319 defines, or includes, a plurality of areas 326 corresponding to different regions of a human heart. As illustrated, the areas 326 are numerically labeled 1-17 (which, e.g., correspond to a standard 17 segment model of a human heart, correspond to 17 segments of the left ventricle of a human heart, etc.). Areas 326 of the map 319 may include basal anterior area 1, basal anteroseptal area 2, basal inferoseptal area 3, basal inferior area 4, basal inferolateral area 5, basal anterolateral area 6, mid-anterior area 7, mid-anteroseptal area 8, mid-inferoseptal area 9, mid-inferior area 10, mid-inferolateral area 11, mid-anterolateral area 12, apical anterior area 13, apical septal area 14, apical inferior area 15, apical lateral area 16, and apex area 17. The inferoseptal and anteroseptal areas of the right ventricle 322 are also illustrated, as well as the right bunch branch (RBB) 25 and left bundle branch (LBB) 27.

In some embodiments, any of the tissue-piercing electrodes of the present disclosure may be implanted in the basal and/or septal region of the left ventricular myocardium of the patient's heart. In particular, the tissue-piercing electrode may be implanted from the triangle of Koch region of the right atrium through the right atrial endocardium and central fibrous body. Once implanted, the tissue-piercing electrode may be positioned in the target implant region 4 (FIGS. 8-9 ), such as the basal and/or septal region of the left ventricular myocardium. With reference to map 319, the basal region includes one or more of the basal anterior area 1, basal anteroseptal area 2, basal inferoseptal area 3, basal inferior area 4, mid-anterior area 7, mid-anteroseptal area 8, mid-inferoseptal area 9, and mid-inferior area 10. With reference to map 319, the septal region includes one or more of the basal anteroseptal area 2, basal anteroseptal area 3, mid-anteroseptal area 8, mid-inferoseptal area 9, and apical septal area 14.

In some embodiments, the tissue-piercing electrode may be positioned in the basal septal region of the left ventricular myocardium when implanted. The basal septal region may include one or more of the basal anteroseptal area 2, basal inferoseptal area 3, mid-anteroseptal area 8, and mid-inferoseptal area 9.

In some embodiments, the tissue-piercing electrode may be positioned in the high inferior/posterior basal septal region of the left ventricular myocardium when implanted. The high inferior/posterior basal septal region of the left ventricular myocardium may include a portion of one or more of the basal inferoseptal area 3 and mid-inferoseptal area 9 (e.g., the basal inferoseptal area only, the mid-inferoseptal area only, or both the basal inferoseptal area and the mid-inferoseptal area). For example, the high inferior/posterior basal septal region may include region 324 illustrated generally as a dashed-line boundary. As shown, the dashed line boundary represents an approximation of where the high inferior/posterior basal septal region is located, which may take a somewhat different shape or size depending on the particular application.

A block diagram of circuitry is depicted in FIG. 11 that may be enclosed within the housings 30 of the device 10 to provide the functions of sensing cardiac signals, determining capture, and/or delivering pacing therapy according to one example or within the housings of any other medical devices described herein. The separate medical device 50 as shown in FIG. 8 may include some or all the same components, which may be configured in a similar manner. The electronic circuitry enclosed within the housing 30 may include software, firmware, and hardware that cooperatively monitor atrial and ventricular electrical cardiac signals, determine whether cardiac system capture has occurred, determine when a cardiac therapy is necessary, and/or deliver electrical pulses to the patient's heart according to programmed therapy mode and pulse control parameters. The electronic circuitry may include a control circuit 80 (e.g., including processing circuitry), a memory 82, a therapy delivery circuit 84, a sensing circuit 86, and/or a telemetry circuit 88. In some examples, the device 10 includes one or more sensors 90 for producing signals that are correlated to one or more physiological functions, states, or conditions of the patient. For example, the sensor(s) 90 may include a patient activity sensor, for use in determining a need for pacing therapy and/or controlling a pacing rate. In other words, the device 10 may include other sensors 90 for sensing signals from the patient for use in determining whether to deliver and/or controlling electrical stimulation therapies delivered by the therapy delivery circuit 84.

The power source 98 may provide power to the circuitry of the device 10 including each of the components 80, 82, 84, 86, 88, 90 as needed. The power source 98 may include one or more energy storage devices, such as one or more rechargeable or non-rechargeable batteries. The connections (not shown) between the power source 98 and each of the components 80, 82, 84, 86, 88, 90 may be understood from the general block diagram illustrated to one of ordinary skill in the art. For example, the power source 98 may be coupled to one or more charging circuits included in the therapy delivery circuit 84 for providing the power used to charge holding capacitors included in the therapy delivery circuit 84 that are discharged at appropriate times under the control of the control circuit 80 for delivering pacing pulses, e.g., according to a dual chamber pacing mode such as DDI®. The power source 98 may also be coupled to components of the sensing circuit 86, such as sense amplifiers, analog-to-digital converters, switching circuitry, etc., sensors 90, the telemetry circuit 88, and the memory 82 to provide power to the various circuits.

The functional blocks shown in FIG. 11 represent functionality included in the device 10 and may include any discrete and/or integrated electronic circuit components that implement analog, and/or digital circuits capable of producing the functions attributed to the medical device 10 described herein. The various components may include processing circuitry, such as an application specific integrated circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group), and memory that execute one or more software or firmware programs, a combinational logic circuit, state machine, or other suitable components or combinations of components that provide the described functionality. The particular form of software, hardware, and/or firmware employed to implement the functionality disclosed herein will be determined primarily by the particular system architecture employed in the medical device and by the particular detection and therapy delivery methodologies employed by the medical device.

The memory 82 may include any volatile, non-volatile, magnetic, or electrical non-transitory computer readable storage media, such as random-access memory (RAM), read-only memory (ROM), non-volatile RAM (NVRAM), electrically-erasable programmable ROM (EEPROM), flash memory, or any other memory device. Furthermore, the memory 82 may include a non-transitory computer readable media storing instructions that, when executed by one or more processing circuits, cause the control circuit 80 and/or other processing circuitry to determine posterior left bundle branch engagement and/or perform a single, dual, or triple chamber calibrated pacing therapy (e.g., single or multiple chamber pacing), or other cardiac therapy functions (e.g., sensing or delivering therapy), attributed to the device 10. The non-transitory computer-readable media storing the instructions may include any of the media listed above.

The control circuit 80 may communicate, e.g., via a data bus, with the therapy delivery circuit 84 and the sensing circuit 86 for sensing cardiac electrical signals and controlling delivery of cardiac electrical stimulation therapies in response to sensed cardiac events, e.g., P-waves and R-waves, or the absence thereof. The tip electrode 42, the distal housing-based electrode 22, and the proximal housing-based electrode 24 may be electrically coupled to the therapy delivery circuit 84 for delivering electrical stimulation pulses to the patient's heart and to the sensing circuit 86 and for sensing cardiac electrical signals.

The sensing circuit 86 may include an atrial (A) sensing channel 87 and a ventricular (V) sensing channel 89. The distal housing-based electrode 22 and the proximal housing-based electrode 24 may be coupled to the atrial sensing channel 87 for sensing atrial signals, e.g., P-waves attendant to the depolarization of the atrial myocardium. In examples that include two or more selectable distal housing-based electrodes, the sensing circuit 86 may include switching circuitry for selectively coupling one or more of the available distal housing-based electrodes to cardiac event detection circuitry included in the atrial sensing channel 87. Switching circuitry may include a switch array, switch matrix, multiplexer, or any other type of switching device suitable to selectively couple components of the sensing circuit 86 to selected electrodes. The tip electrode 42 and the proximal housing-based electrode 24 may be coupled to the ventricular sensing channel 89 for sensing ventricular signals, e.g., R-waves attendant to the depolarization of the ventricular myocardium.

Each of the atrial sensing channel 87 and the ventricular sensing channel 89 may include cardiac event detection circuitry for detecting P-waves and R-waves, respectively, from the cardiac electrical signals received by the respective sensing channels. The cardiac event detection circuitry included in each of the channels 87 and 89 may be configured to amplify, filter, digitize, and rectify the cardiac electrical signal received from the selected electrodes to improve the signal quality for detecting cardiac electrical events. The cardiac event detection circuitry within each channel 87 and 89 may include one or more sense amplifiers, filters, rectifiers, threshold detectors, comparators, analog-to-digital converters (ADCs), timers, or other analog or digital components. A cardiac event sensing threshold, e.g., a P-wave sensing threshold and an R-wave sensing threshold, may be automatically adjusted by each respective sensing channel 87 and 89 under the control of the control circuit 80, e.g., based on timing intervals and sensing threshold values determined by the control circuit 80, stored in the memory 82, and/or controlled by hardware, firmware, and/or software of the control circuit 80 and/or the sensing circuit 86.

Upon detecting a cardiac electrical event based on a sensing threshold crossing, the sensing circuit 86 may produce a sensed event signal that is passed to the control circuit 80. For example, the atrial sensing channel 87 may produce a P-wave sensed event signal in response to a P-wave sensing threshold crossing. The ventricular sensing channel 89 may produce an R-wave sensed event signal in response to an R-wave sensing threshold crossing. The sensed event signals may be used by the control circuit 80 for setting pacing escape interval timers that control the basic time intervals used for scheduling cardiac pacing pulses. A sensed event signal may trigger or inhibit a pacing pulse depending on the particular programmed pacing mode. For example, a P-wave sensed event signal received from the atrial sensing channel 87 may cause the control circuit 80 to inhibit a scheduled atrial pacing pulse and schedule a ventricular pacing pulse at a programmed atrioventricular (A-V) pacing interval. If an R-wave is sensed before the A-V pacing interval expires, the ventricular pacing pulse may be inhibited. If the A-V pacing interval expires before the control circuit 80 receives an R-wave sensed event signal from the ventricular sensing channel 89, the control circuit 80 may use the therapy delivery circuit 84 to deliver the scheduled ventricular pacing pulse synchronized to the sensed P-wave.

In some examples, the device 10 may be configured to deliver a variety of pacing therapies including bradycardia pacing, cardiac resynchronization therapy, post-shock pacing, and/or tachycardia-related therapy, such as ATP, among others. For example, the device 10 may be configured to detect non-sinus tachycardia and deliver ATP. The control circuit 80 may determine cardiac event time intervals, e.g., P-P intervals between consecutive P-wave sensed event signals received from the atrial sensing channel 87, R-R intervals between consecutive R-wave sensed event signals received from the ventricular sensing channel 89, and P-R and/or R-P intervals received between P-wave sensed event signals and R-wave sensed event signals. These intervals may be compared to tachycardia detection intervals for detecting non-sinus tachycardia. Tachycardia may be detected in a given heart chamber based on a threshold number of tachycardia detection intervals being detected.

The therapy delivery circuit 84 may include atrial pacing circuit 83 and ventricular pacing circuit 85. Each pacing circuit 83, 85 may include charging circuitry, one or more charge storage devices such as one or more low voltage holding capacitors, an output capacitor, and/or switching circuitry that controls when the holding capacitor(s) are charged and discharged across the output capacitor to deliver a pacing pulse to the pacing electrode vector coupled to respective pacing circuits 83, 85. The tip electrode 42 and the proximal housing-based electrode 24 may be coupled to the ventricular pacing circuit 85 as a bipolar cathode and anode pair for delivering ventricular pacing pulses, e.g., upon expiration of an A-V or V-V pacing interval set by the control circuit 80 for providing atrial-synchronized ventricular pacing and a basic lower ventricular pacing rate.

The atrial pacing circuit 83 may be coupled to the distal housing-based electrode 22 and the proximal housing-based electrode 24 to deliver atrial pacing pulses. The control circuit 80 may set one or more atrial pacing intervals according to a programmed lower pacing rate or a temporary lower rate set according to a rate-responsive sensor indicated pacing rate. Atrial pacing circuit may be controlled to deliver an atrial pacing pulse if the atrial pacing interval expires before a P-wave sensed event signal is received from the atrial sensing channel 87. The control circuit 80 starts an A-V pacing interval in response to a delivered atrial pacing pulse to provide synchronized multiple chamber pacing (e.g., dual or triple chamber pacing).

Charging of a holding capacitor of the atrial or ventricular pacing circuit 83, 85 to a programmed pacing voltage amplitude and discharging of the capacitor for a programmed pacing pulse width may be performed by the therapy delivery circuit 84 according to control signals received from the control circuit 80. For example, a pace timing circuit included in the control circuit 80 may include programmable digital counters set by a microprocessor of the control circuit 80 for controlling the basic pacing time intervals associated with various single chamber or multiple chamber pacing (e.g., dual or triple chamber pacing) modes or anti-tachycardia pacing sequences. The microprocessor of the control circuit 80 may also set the amplitude, pulse width, polarity, or other characteristics of the cardiac pacing pulses, which may be based on programmed values stored in the memory 82.

Control parameters utilized by the control circuit 80 for sensing cardiac events and controlling pacing therapy delivery may be programmed into the memory 82 via the telemetry circuit 88, which may also be described as a communication interface. The telemetry circuit 88 includes a transceiver and antenna for communicating with an external device, such as a programmer or home monitor, using radio frequency communication or other communication protocols. The control circuit 80 may use the telemetry circuit 88 to receive downlink telemetry from and send uplink telemetry to the external device. In some cases, the telemetry circuit 88 may be used to transmit and receive communication signals to/from another medical device implanted in the patient.

The techniques described in this disclosure, including those attributed to the IMD 10, device 50, the computing apparatus 140, and the computing device 160 and/or various constituent components, may be implemented, at least in part, in hardware, software, firmware, or any combination thereof. For example, various aspects of the techniques may be implemented within one or more processors, including one or more microprocessors, DSPs, ASICs, FPGAs, or any other equivalent integrated or discrete logic circuitry, as well as any combinations of such components, embodied in programmers, such as physician or patient programmers, stimulators, image processing devices, or other devices. The term “module,” “processor,” or “processing circuitry” may generally refer to any of the foregoing logic circuitry, alone or in combination with other logic circuitry, or any other equivalent circuitry.

Such hardware, software, and/or firmware may be implemented within the same device or within separate devices to support the various operations and functions described in this disclosure. In addition, any of the described units, modules, or components may be implemented together or separately as discrete but interoperable logic devices. Depiction of different features as modules or units is intended to highlight different functional aspects and does not necessarily imply that such modules or units must be realized by separate hardware or software components. Rather, functionality associated with one or more modules or units may be performed by separate hardware or software components or integrated within common or separate hardware or software components.

When implemented in software, the functionality ascribed to the systems, devices and techniques described in this disclosure may be embodied as instructions on a computer-readable medium such as RAM, ROM, NVRAM, EEPROM, FLASH memory, magnetic data storage media, optical data storage media, or the like. The instructions may be executed by processing circuitry and/or one or more processors to support one or more aspects of the functionality described in this disclosure.

All references and publications cited herein are expressly incorporated herein by reference in their entirety for all purposes, except to the extent any aspect incorporated directly contradicts this disclosure.

All scientific and technical terms used herein have meanings commonly used in the art unless otherwise specified. The definitions provided herein are to facilitate understanding of certain terms used frequently herein and are not meant to limit the scope of the present disclosure.

Unless otherwise indicated, all numbers expressing feature sizes, amounts, and physical properties used in the specification and claims may be understood as being modified either by the term “exactly” or “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in the foregoing specification and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by those skilled in the art utilizing the teachings disclosed herein or, for example, within typical ranges of experimental error.

The recitation of numerical ranges by endpoints includes all numbers subsumed within that range (e.g. 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5) and any range within that range. Herein, the terms “up to” or “no greater than” a number (e.g., up to 50) includes the number (e.g., 50), and the term “no less than” a number (e.g., no less than 5) includes the number (e.g., 5).

The terms “coupled” or “connected” refer to elements being attached to each other either directly (in direct contact with each other) or indirectly (having one or more elements between and attaching the two elements). Either term may be modified by “operatively” and “operably,” which may be used interchangeably, to describe that the coupling or connection is configured to allow the components to interact to carry out at least some functionality (for example, a first medical device may be operatively coupled to another medical device to transmit information in the form of data or to receive data therefrom).

Terms related to orientation, such as “top,” “bottom,” “side,” and “end,” are used to describe relative positions of components and are not meant to limit the orientation of the embodiments contemplated. For example, an embodiment described as having a “top” and “bottom” also encompasses embodiments thereof rotated in various directions unless the content clearly dictates otherwise.

Reference to “one embodiment,” “an embodiment,” “certain embodiments,” or “some embodiments,” etc., means that a particular feature, configuration, composition, or characteristic described in connection with the embodiment is included in at least one embodiment of the disclosure. Thus, the appearances of such phrases in various places throughout are not necessarily referring to the same embodiment of the disclosure. Furthermore, the particular features, configurations, compositions, or characteristics may be combined in any suitable manner in one or more embodiments.

As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” encompass embodiments having plural referents, unless the content clearly dictates otherwise. As used in this specification and the appended claims, the term “or” is generally employed in its sense including “and/or” unless the content clearly dictates otherwise.

As used herein, “have,” “having,” “include,” “including,” “comprise,” “comprising” or the like are used in their open-ended sense, and generally mean “including, but not limited to.” It will be understood that “consisting essentially of,” “consisting of,” and the like are subsumed in “comprising,” and the like.

The term “and/or” means one or all the listed elements or a combination of at least two of the listed elements. The phrases “at least one of,” “comprises at least one of,” and “one or more of” followed by a list refers to any one of the items in the list and any combination of two or more items in the list.

ILLUSTRATIVE EXAMPLES

Example 1: A system comprising:

-   -   an electrode apparatus comprising a plurality of external         electrodes to be disposed proximate a patient's skin; and     -   a computing apparatus comprising processing circuitry and         operably coupled to the electrode apparatus, the computing         apparatus configured to:         -   monitor intrinsic electrical activity of the patient using             the plurality of external electrodes of the electrode             apparatus,         -   generate a plurality of cardiac breakthrough maps based on             the monitored intrinsic activity over a time period, wherein             each cardiac breakthrough map is a spatial representation of             electrocardiographic potential; and         -   determine a cardiac conduction system block location based             on the plurality of generated cardiac breakthrough maps.

Example 2: A method comprising:

-   -   monitoring intrinsic electrical activity of the patient using a         plurality of external electrodes disposed proximate a patient's         skin;     -   generating a plurality of cardiac breakthrough maps based on the         monitored intrinsic activity over a time period, wherein each         cardiac breakthrough map is a spatial representation of         electrocardiographic potential; and     -   determining a cardiac conduction system block location based on         the plurality of generated cardiac breakthrough maps.

Example 3: The system of Example 1 or method of Example 2, wherein each of the plurality of cardiac breakthrough maps are generated according to a sampling interval following QRS onset of a single heartbeat.

Example 4: The system or method of Example 3, wherein the sampling interval is less than or equal to 5 milliseconds.

Example 5: The system or method as in any one of Examples 1-4, wherein determining the cardiac conduction system block location based on the generated cardiac breakthrough maps comprises determining a spatial location of a breakthrough within the plurality of cardiac breakthrough maps where the cardiac potential is less than or equal to a breakthrough threshold.

Example 6: The system or method of Example 5, wherein the breakthrough threshold is less than or equal to −1 millivolts.

Example 7: The system or method as in any one of Examples 5-6, wherein determining the cardiac conduction system block location based on the generated cardiac breakthrough maps comprises determining the cardiac conduction system block location is distally located along the cardiac conduction system if the spatial location of the breakthrough is located within a left anterior region of the generated cardiac breakthrough maps.

Example 8: The system or method as in any one of Examples 1-7, wherein determining the cardiac conduction system block location based on the generated cardiac breakthrough maps comprises determining the cardiac conduction system block location is proximally located along the cardiac conduction system if the spatial location of the breakthrough is not located within a left anterior region of the generated cardiac breakthrough maps.

Example 9: The system or method as in any one of Examples 1-8, wherein the system is further configured to execute or the method further comprises displaying the plurality of cardiac breakthrough maps on a graphical user interface.

Example 10: The system or method as in any one of Examples 1-9, wherein the plurality of cardiac breakthrough maps comprise:

-   -   an anterior region spatially representing cardiac potential of         the anterior of the patient's heart; and     -   a posterior region spatially representing cardiac potential of         the posterior of the patient's heart.

Example 11: A system comprising:

-   -   an electrode apparatus comprising a plurality of external         electrodes to be disposed proximate a patient's skin;     -   a display comprising a graphical user interface; and     -   a computing apparatus comprising processing circuitry and         operably coupled to the electrode apparatus and the display, the         computing apparatus configured to:         -   monitor intrinsic electrical activity of the patient using             the plurality of external electrodes of the electrode             apparatus,         -   generate a plurality of cardiac breakthrough maps based on             the monitored intrinsic activity over a time period, wherein             each cardiac breakthrough map is a spatial representation of             electrocardiographic potential; and         -   display the plurality of generated cardiac breakthrough maps             on the graphical user interface.

Example 12: The system of Example 11, wherein displaying the plurality of cardiac breakthrough maps on the graphical user interface comprises displaying each of the plurality of cardiac breakthrough maps on the graphical user interface sequentially.

Example 13: The system of Example 12, wherein the computing apparatus is further configured to allow a user to interact with the graphical user interface to selectively traverse the sequentially displayed plurality of cardiac breakthrough maps on the graphical user interface.

Example 14: The system as in any one of Examples 11-13, wherein the plurality of cardiac breakthrough maps comprise:

-   -   an anterior region spatially representing cardiac potential of         the anterior of the patient's heart; and     -   a posterior region spatially representing cardiac potential of         the posterior of the patient's heart.

Example 15: The system as in any one of Examples 11-14, wherein the computing apparatus is further configured determine a spatial location of a breakthrough based on the plurality of cardiac breakthrough maps, wherein displaying the plurality of cardiac breakthrough maps on the graphical user interface comprises displaying at least one cardiac breakthrough map comprises the spatial location of the breakthrough.

Example 16: The system as in any one of Examples 11-15, wherein the computing apparatus is further configured to:

-   -   determine whether the cardiac conduction system block location         is proximally located or distally located along the cardiac         conduction system based on the plurality of generated cardiac         breakthrough maps on the graphical user interface; and     -   display on the graphical user interface an indication of whether         the cardiac conduction system block location is proximally         located or distally located along the cardiac conduction system.

Example 17: A system comprising:

-   -   an electrode apparatus comprising a plurality of external         electrodes to be disposed proximate a patient's skin; and     -   computing apparatus comprising processing circuitry and coupled         to the electrode apparatus, the computer apparatus configured         to:         -   monitor intrinsic electrical activity of the patient using             the plurality of external electrodes of the electrode             apparatus;         -   generate baseline electrical heterogeneity information (EHI)             based on the monitored intrinsic electrical activity;         -   monitor paced electrical activity of the patient using the             plurality of external electrodes of the electrode apparatus             during delivery of cardiac conduction system pacing therapy;         -   generate paced EHI based on the monitored paced electrical             activity; and         -   determine whether the cardiac conduction system pacing             therapy is effective based on the baseline and the paced             EHI.

Example 18: A method comprising:

-   -   monitoring intrinsic electrical activity of the patient using a         plurality of external electrodes disposed proximate the         patient's skin;     -   generating baseline electrical heterogeneity information (EHI)         based on the monitored intrinsic electrical activity;     -   monitoring paced electrical activity of the patient using the         plurality of external electrodes of the electrode apparatus         during delivery of cardiac conduction system pacing therapy;     -   generating paced EHI based on the monitored paced electrical         activity; and     -   determining whether the cardiac conduction system pacing therapy         is effective based on the baseline and the paced EHI.

Example 19: The system of Example 17 or the method of Example 18, wherein the cardiac conduction system pacing therapy is delivered at a paced AV delay that between 40% to 80% of an intrinsic AV delay, wherein the paced AV delay is a time period between a sensed atrial event and delivery of cardiac conduction system pacing therapy, wherein the intrinsic AV delay is a time period between a sensed atrial event and an intrinsic ventricular event.

Example 20: The system or method as set forth in any one of Examples 17-19, wherein generating baseline EHI comprises generating a baseline standard deviation of surrogate cardiac electrical activation times (SDAT) based on the monitored intrinsic electrical activity, wherein generating paced EHI comprises generating a paced SDAT based on the monitored paced electrical activity.

Example 22: The system or method of Example 21, wherein determining whether the cardiac conduction system pacing therapy is effective based on the baseline and the paced EHI comprises determining that the cardiac conduction system pacing therapy is effective if the paced SDAT is less than 90% of the baseline SDAT.

Example 22: The system or method as set forth in any one of Examples 17-21, wherein the plurality of external electrodes comprise a plurality of left external electrodes positioned to the left side of the patient's torso, wherein generating paced EHI comprises generating a paced left-sided standard deviation of surrogate cardiac electrical activation times (LVED) based on the monitored paced electrical activity using the plurality of left external electrodes.

Example 23: The system or method of Example 22, wherein determining whether the cardiac conduction system pacing therapy is effective based on the baseline and the paced EHI comprises determining that the cardiac conduction system pacing therapy is effective if the paced LVED is less than 25 milliseconds.

Example 24: The system or method as set forth in any one of Examples 17-21, wherein the computing apparatus is further configured to execute or the method further comprises:

-   -   determining whether cardiac activation delay is located on the         left or right side of the left ventricle based on the monitored         paced electrical activity in response to determining that the         cardiac conduction system pacing therapy is not effective;     -   indicating that a left ventricular lead will assist the cardiac         conduction system pacing therapy if the cardiac activation delay         is located on the left side of the left ventricle; and     -   indicating that a right ventricular lead will assist the cardiac         conduction system pacing therapy if the cardiac activation delay         is located on the right side of the left ventricle.

Example 25: The system or method of Example 24, wherein the computing apparatus is further configured to execute or the method further comprises:

-   -   monitoring combined paced electrical activity of the patient         using the plurality of external electrodes of the electrode         apparatus during delivery of cardiac conduction system pacing         therapy and pacing therapy using a right or left ventricular         lead;     -   generating combined paced EHI based on the monitored combined         paced electrical activity; and     -   determining whether a location of the right or lead ventricular         lead is effective is effective based on the combined paced EHI         and the baseline EHI.

Example 26: The system or method as set forth in any one of Examples 17-25, wherein the cardiac conduction system pacing therapy comprises one or more of ventricle-from-atrium (VfA) pacing therapy, His bundle pacing therapy, and intraseptal left ventricular endocardial pacing.

This disclosure has been provided with reference to illustrative embodiments and examples and is not meant to be construed in a limiting sense. As described previously, one skilled in the art will recognize that other various illustrative applications may use the techniques as described herein to take advantage of the beneficial characteristics of the systems, devices, and methods described herein. Various modifications of the illustrative embodiments and examples will be apparent upon reference to this description. 

What is claimed:
 1. A system comprising: an electrode apparatus comprising a plurality of external electrodes configured to be disposed proximate a patient's skin; a display depicting a graphical user interface; and a computing apparatus comprising processing circuitry and operably coupled to the electrode apparatus and the display, the computing apparatus configured to: monitor intrinsic cardiac electrical activity of the patient using the plurality of external electrodes of the electrode apparatus; determine a QRS onset of a single heartbeat based on the monitored intrinsic electrical activity; generate a plurality of cardiac breakthrough maps based on the monitored intrinsic activity over a time period comprising generating each of the plurality of cardiac breakthrough maps according to a sampling interval following the determined QRS onset of the single heartbeat, wherein each cardiac breakthrough map is a spatial representation of electrocardiographic voltage across the skin of the patient corresponding to electrocardiographic voltage of the heart at a different time within the time period; determine a cardiac conduction system block location based on the plurality of generated cardiac breakthrough maps; and display the plurality of cardiac breakthrough maps on the graphical user interface of the display.
 2. The system of claim 1, wherein the sampling interval is less than or equal to 5 milliseconds.
 3. The system of claim 1, wherein determining the cardiac conduction system block location based on the generated cardiac breakthrough maps comprises determining a spatial location of a breakthrough within the plurality of cardiac breakthrough maps where the electrocardiographic voltage is less than or equal to a breakthrough threshold.
 4. The system of claim 3, wherein the breakthrough threshold is less than or equal to −1 millivolts.
 5. The system of claim 3, wherein determining the cardiac conduction system block location based on the generated cardiac breakthrough maps comprises determining the cardiac conduction system block location is distally located along the cardiac conduction system when the spatial location of the breakthrough is located within a left anterior region of the generated cardiac breakthrough maps.
 6. The system of claim 3, wherein determining the cardiac conduction system block location based on the generated cardiac breakthrough maps comprises determining the cardiac conduction system block location is proximally located along the cardiac conduction system when the spatial location of the breakthrough is not located within a left anterior region of the generated cardiac breakthrough maps.
 7. The system of claim 1, wherein the plurality of cardiac breakthrough maps comprise: an anterior region spatially representing electrocardiographic voltage of the anterior of the patient's heart; and a posterior region spatially representing electrocardiographic voltage of the posterior of the patient's heart.
 8. A method comprising: monitoring intrinsic cardiac electrical activity of a patient using a plurality of external electrodes disposed proximate the patient's skin; determining a QRS onset of a single heartbeat based on the monitored intrinsic electrical activity; generating a plurality of cardiac breakthrough maps based on the monitored intrinsic activity over a time period comprises generating each of the plurality of cardiac breakthrough maps according to a sampling interval following the determined QRS onset of the single heartbeat, wherein each cardiac breakthrough map is a spatial representation of electrocardiographic voltage across the skin of the patient corresponding to electrocardiographic voltage of the heart at a different time within the time period; determining a cardiac conduction system block location based on the plurality of generated cardiac breakthrough maps; and displaying the plurality of cardiac breakthrough maps on a graphical user interface of a display.
 9. The method of claim 8, wherein the sampling interval is less than or equal to 5 milliseconds.
 10. The method of claim 8, wherein determining the cardiac conduction system block location based on the generated cardiac breakthrough maps comprises determining a spatial location of a breakthrough within the plurality of cardiac breakthrough maps where the electrocardiographic voltage is less than or equal to a breakthrough threshold.
 11. The method of claim 10, wherein the breakthrough threshold is less than or equal to −1 millivolts.
 12. The method of claim 10, wherein determining the cardiac conduction system block location based on the generated cardiac breakthrough maps comprises determining the cardiac conduction system block location is distally located along the cardiac conduction system when the spatial location of the breakthrough is located within a left anterior region of the generated cardiac breakthrough maps.
 13. The method of claim 10, wherein determining the cardiac conduction system block location based on the generated cardiac breakthrough maps comprises determining the cardiac conduction system block location is proximally located along the cardiac conduction system when the spatial location of the breakthrough is not located within a left anterior region of the generated cardiac breakthrough maps.
 14. The method of claim 8, wherein the plurality of cardiac breakthrough maps comprise: an anterior region spatially representing electrocardiographic voltage of the anterior of the patient's heart; and a posterior region spatially representing electrocardiographic voltage of the posterior of the patient's heart.
 15. A system comprising: an electrode apparatus comprising a plurality of external electrodes configured to be disposed proximate a patient's skin; a display depicting a graphical user interface; and a computing apparatus comprising processing circuitry and operably coupled to the electrode apparatus and the display, the computing apparatus configured to: monitor intrinsic cardiac electrical activity of the patient using the plurality of external electrodes of the electrode apparatus; generate a plurality of cardiac breakthrough maps based on the monitored intrinsic activity over a time period, wherein each cardiac breakthrough map is a spatial representation of electrocardiographic voltage across the skin of the patient corresponding to electrocardiographic voltage of the heart at a different time within the time period; determine a cardiac conduction system block location based on the plurality of generated cardiac breakthrough maps comprising determining a spatial location of a breakthrough within the plurality of cardiac breakthrough maps where the electrocardiographic voltage is less than or equal to a breakthrough threshold; and display the plurality of cardiac breakthrough maps on the graphical user interface of the display.
 16. The system of claim 15, wherein the breakthrough threshold is less than or equal to −1 millivolts.
 17. The system of claim 15, wherein determining the cardiac conduction system block location based on the generated cardiac breakthrough maps comprises determining the cardiac conduction system block location is distally located along the cardiac conduction system when the spatial location of the breakthrough is located within a left anterior region of the generated cardiac breakthrough maps.
 18. The system of claim 15, wherein determining the cardiac conduction system block location based on the generated cardiac breakthrough maps comprises determining the cardiac conduction system block location is proximally located along the cardiac conduction system when the spatial location of the breakthrough is not located within a left anterior region of the generated cardiac breakthrough maps.
 19. The system of claim 15, wherein the plurality of cardiac breakthrough maps comprise: an anterior region spatially representing electrocardiographic voltage of the anterior of the patient's heart; and a posterior region spatially representing electrocardiographic voltage of the posterior of the patient's heart.
 20. A method comprising: monitoring intrinsic cardiac electrical activity of a patient using a plurality of external electrodes disposed proximate the patient's skin; generating a plurality of cardiac breakthrough maps based on the monitored intrinsic activity over a time period, wherein each cardiac breakthrough map is a spatial representation of electrocardiographic voltage across the skin of the patient corresponding to electrocardiographic voltage of the heart at a different time within the time period; determining a cardiac conduction system block location based on the plurality of generated cardiac breakthrough maps comprising determining a spatial location of a breakthrough within the plurality of cardiac breakthrough maps where the electrocardiographic voltage is less than or equal to a breakthrough threshold; and displaying the plurality of cardiac breakthrough maps on a graphical user interface of a display.
 21. The method of claim 20, wherein determining the cardiac conduction system block location based on the generated cardiac breakthrough maps comprises determining a spatial location of a breakthrough within the plurality of cardiac breakthrough maps where the electrocardiographic voltage is less than or equal to a breakthrough threshold.
 22. The method of claim 20, wherein the breakthrough threshold is less than or equal to −1 millivolts.
 23. The method of claim 20, wherein determining the cardiac conduction system block location based on the generated cardiac breakthrough maps comprises determining the cardiac conduction system block location is distally located along the cardiac conduction system when the spatial location of the breakthrough is located within a left anterior region of the generated cardiac breakthrough maps.
 24. The method of claim 20, wherein determining the cardiac conduction system block location based on the generated cardiac breakthrough maps comprises determining the cardiac conduction system block location is proximally located along the cardiac conduction system when the spatial location of the breakthrough is not located within a left anterior region of the generated cardiac breakthrough maps.
 25. The method of claim 20, wherein the plurality of cardiac breakthrough maps comprise: an anterior region spatially representing electrocardiographic voltage of the anterior of the patient's heart; and a posterior region spatially representing electrocardiographic voltage of the posterior of the patient's heart. 